diff --git a/lib/get-sourcemap-content.js b/lib/get-sourcemap-content.js
new file mode 100644
index 0000000..d8e7204
--- /dev/null
+++ b/lib/get-sourcemap-content.js
@@ -0,0 +1,29 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const srcURL = require('source-map-url');
+
+module.exports = function getSourceMapContent(src, inFileDirname, relativePath, silent) {
+  let urls = [];
+  let matchedUrl;
+  while ((matchedUrl = srcURL.getFrom(src)) !== null) {
+    urls.push(matchedUrl);
+    src = srcURL.removeFrom(src);
+  }
+  if (urls.length) {
+    for (let i = urls.length - 1; i >= 0; --i) {
+      let sourceMapPath = path.join(inFileDirname, urls[i]);
+      if (fs.existsSync(sourceMapPath)) {
+        return JSON.parse(fs.readFileSync(sourceMapPath));
+      }
+    }
+    if (!silent) {
+      console.warn(
+        `[WARN] (broccoli-uglify-sourcemap) ${urls
+          .map(u => `"${u}"`)
+          .join(', ')} referenced in "${relativePath}" could not be found`
+      );
+    }
+  }
+};
diff --git a/lib/process-file.js b/lib/process-file.js
index a908293..bff4445 100644
--- a/lib/process-file.js
+++ b/lib/process-file.js
@@ -5,7 +5,7 @@ const defaults = require('lodash.defaultsdeep');
 const fs = require('fs');
 const mkdirp = require('mkdirp');
 const path = require('path');
-const srcURL = require('source-map-url');
+const getSourceMapContent = require('./get-sourcemap-content');
 
 const terser = require('terser');
 
@@ -38,14 +38,9 @@ module.exports = function processFile(inFile, outFile, relativePath, outDir, sil
 
     let sourceMap = { filename, url };
 
-    if (srcURL.existsIn(src)) {
-      let url = srcURL.getFrom(src);
-      let sourceMapPath = path.join(path.dirname(inFile), url);
-      if (fs.existsSync(sourceMapPath)) {
-        sourceMap.content = JSON.parse(fs.readFileSync(sourceMapPath));
-      } else if (!silent) {
-        console.warn(`[WARN] (broccoli-uglify-sourcemap) "${url}" referenced in "${relativePath}" could not be found`);
-      }
+    let content = getSourceMapContent(src, path.dirname(inFile), relativePath, silent);
+    if (content) {
+      sourceMap.content = content;
     }
 
     options = defaults(options, { sourceMap });
@@ -71,11 +66,22 @@ module.exports = function processFile(inFile, outFile, relativePath, outDir, sil
     let newSourceMap = JSON.parse(result.map);
 
     newSourceMap.sources = newSourceMap.sources.map(function(path) {
-      // If out output file has the same name as one of our original
-      // sources, they will shadow eachother in Dev Tools. So instead we
-      // alter the reference to the upstream file.
       if (path === relativePath) {
-        path = path.replace(/\.js$/, '-orig.js');
+        // If out output file has the same name as one of our original
+        // sources, they will shadow eachother in Dev Tools. So instead we
+        // alter the reference to the upstream file.
+        return path.replace(/\.js$/, '-orig.js');
+      } else if (path === '0') {
+        // In [terser-js](https://github.com/terser-js/terser#source-map-options),
+        // sources are always 0 if old sourcemaps are not provided.
+        // The value passed for `sourceMap.url` is only used to set
+        // `//# sourceMappingURL=out.js.map` in `result.code`.
+        // The value of `filename` is only used to set `file` attribute
+        // in source map file.
+        // In broccoli-uglify-sourcemap we know in this case we are generating
+        // sourcemap for the file we are processing, changing 0 to the actual
+        // file gives us the correct source.
+        return relativePath;
       }
       return path;
     });
diff --git a/test/__snapshots__/test.js.snap b/test/__snapshots__/test.js.snap
index e144c73..9842174 100644
--- a/test/__snapshots__/test.js.snap
+++ b/test/__snapshots__/test.js.snap
@@ -5,6 +5,9 @@ Object {
   "inside": Object {
     "with-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}",
   "something.css": "#id {
     background: white;
@@ -40,15 +43,20 @@ function third(){
 //# sourceMappingURL=with-upstream-sourcemap.map",
     "with-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"],\\"names\\":[],\\"mappings\\":\\";AAAA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;ACPA;AACA;AACA;ACFA;AACA;AACA;AACA;AACA;AACA;ACLA;AACA;AACA;\\",\\"file\\":\\"with-upstream-sourcemap.js\\"}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
+//# sourceMappingURL=with-multi-sourcemap.map",
+    "with-multi-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-multi-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
 //# sourceMappingURL=no-upstream-sourcemap.map",
-  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
+  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"no-upstream-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
   "something.css": "#id {
     background: white;
 }",
   "with-broken-sourcemap.js": "function meaningOfLife(){throw new Error(42)}
 //# sourceMappingURL=with-broken-sourcemap.map",
-  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"with-broken-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
 }
 `;
 
@@ -56,7 +64,7 @@ exports[`broccoli-uglify-sourcemap can handle ES6 code 1`] = `
 Object {
   "es6.js": "class Foo{bar(){console.log(this.baz)}}let{bar:bar}=Foo.prototype;
 //# sourceMappingURL=es6.map",
-  "es6.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"Foo\\",\\"[object Object]\\",\\"console\\",\\"log\\",\\"this\\",\\"baz\\",\\"bar\\",\\"prototype\\"],\\"mappings\\":\\"AAAA,MAAMA,IACJC,MACEC,QAAQC,IAAIC,KAAKC,MAIrB,IAAIC,IAAEA,KAAQN,IAAIO\\",\\"file\\":\\"es6.js\\"}",
+  "es6.map": "{\\"version\\":3,\\"sources\\":[\\"es6.js\\"],\\"names\\":[\\"Foo\\",\\"[object Object]\\",\\"console\\",\\"log\\",\\"this\\",\\"baz\\",\\"bar\\",\\"prototype\\"],\\"mappings\\":\\"AAAA,MAAMA,IACJC,MACEC,QAAQC,IAAIC,KAAKC,MAIrB,IAAIC,IAAEA,KAAQN,IAAIO\\",\\"file\\":\\"es6.js\\"}",
 }
 `;
 
@@ -67,15 +75,20 @@ Object {
 //# sourceMappingURL=with-upstream-sourcemap.map",
     "with-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-upstream-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
+//# sourceMappingURL=with-multi-sourcemap.map",
+    "with-multi-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-multi-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
 //# sourceMappingURL=no-upstream-sourcemap.map",
-  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
+  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"no-upstream-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
   "something.css": "#id {
     background: white;
 }",
   "with-broken-sourcemap.js": "function meaningOfLife(){throw new Error(42)}
 //# sourceMappingURL=with-broken-sourcemap.map",
-  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"with-broken-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
 }
 `;
 
@@ -86,15 +99,20 @@ Object {
 //# sourceMappingURL=with-upstream-sourcemap.map",
     "with-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-upstream-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
+//# sourceMappingURL=with-multi-sourcemap.map",
+    "with-multi-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-multi-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
 //# sourceMappingURL=no-upstream-sourcemap.map",
-  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
+  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"no-upstream-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
   "something.css": "#id {
     background: white;
 }",
   "with-broken-sourcemap.js": "function meaningOfLife(){throw new Error(42)}
 //# sourceMappingURL=with-broken-sourcemap.map",
-  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"with-broken-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
 }
 `;
 
@@ -111,15 +129,20 @@ Object {
 //# sourceMappingURL=with-upstream-sourcemap.map",
     "with-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-upstream-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
+//# sourceMappingURL=with-multi-sourcemap.map",
+    "with-multi-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-multi-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
 //# sourceMappingURL=no-upstream-sourcemap.map",
-  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
+  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"no-upstream-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
   "something.css": "#id {
     background: white;
 }",
   "with-broken-sourcemap.js": "function meaningOfLife(){throw new Error(42)}
 //# sourceMappingURL=with-broken-sourcemap.map",
-  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"with-broken-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
 }
 `;
 
@@ -130,10 +153,15 @@ Object {
 //# sourceMappingURL=/maps/with-upstream-sourcemap.map",
   },
   "maps": Object {
-    "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
-    "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+    "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"no-upstream-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
+    "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"with-broken-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+    "with-multi-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-multi-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
     "with-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-upstream-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
+//# sourceMappingURL=/maps/with-multi-sourcemap.map",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
 //# sourceMappingURL=/maps/no-upstream-sourcemap.map",
   "something.css": "#id {
@@ -150,13 +178,17 @@ Object {
     "with-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}",
     "with-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-upstream-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}",
+    "with-multi-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-multi-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}",
-  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
+  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"no-upstream-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
   "something.css": "#id {
     background: white;
 }",
   "with-broken-sourcemap.js": "function meaningOfLife(){throw new Error(42)}",
-  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"with-broken-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
 }
 `;
 
@@ -167,14 +199,19 @@ Object {
 //# sourceMappingURL=https://example.com/with-upstream-sourcemap.map",
     "with-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-upstream-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
   },
+  "multi": Object {
+    "with-multi-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
+//# sourceMappingURL=https://example.com/with-multi-sourcemap.map",
+    "with-multi-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"/inner/first.js\\",\\"/inner/second.js\\",\\"/other/fourth.js\\",\\"/other/third.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AAAA,SAAAA,gBAEA,MAAA,IAAAC,MADA,IAIA,SAAAC,OACA,MAAA,IAAAD,MAAA,QCNA,SAAAE,gBACA,MAAA,IAAAF,MAAA,kBCEA,SAAAG,SACA,MAAA,IAAAH,MAAA,UCJA,SAAAI,QACA,MAAA,IAAAJ,MAAA\\",\\"file\\":\\"with-multi-sourcemap.js\\",\\"sourcesContent\\":[\\"function meaningOfLife() {\\\\n  var thisIsALongLocal = 42;\\\\n  throw new Error(thisIsALongLocal);\\\\n}\\\\n\\\\nfunction boom() {\\\\n  throw new Error('boom');\\\\n}\\\\n\\",\\"function somethingElse() {\\\\n  throw new Error(\\\\\\"somethign else\\\\\\");\\\\n}\\\\n\\",\\"\\\\n// Hello world\\\\n\\\\nfunction fourth(){\\\\n  throw new Error('fourth');\\\\n}\\\\n\\",\\"function third(){\\\\n  throw new Error(\\\\\\"oh no\\\\\\");\\\\n}\\\\n\\"]}",
+  },
   "no-upstream-sourcemap.js": "function meaningOfLife(){throw new Error(42)}function boom(){throw new Error(\\"boom\\")}function somethingElse(){throw new Error(\\"somethign else\\")}function fourth(){throw new Error(\\"fourth\\")}function third(){throw new Error(\\"oh no\\")}
 //# sourceMappingURL=https://example.com/no-upstream-sourcemap.map",
-  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
+  "no-upstream-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"no-upstream-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\",\\"boom\\",\\"somethingElse\\",\\"fourth\\",\\"third\\"],\\"mappings\\":\\"AACA,SAASA,gBAEP,MAAM,IAAIC,MADa,IAIzB,SAASC,OACP,MAAM,IAAID,MAAM,QAGlB,SAASE,gBACP,MAAM,IAAIF,MAAM,kBAMlB,SAASG,SACP,MAAM,IAAIH,MAAM,UAGlB,SAASI,QACP,MAAM,IAAIJ,MAAM\\",\\"file\\":\\"no-upstream-sourcemap.js\\"}",
   "something.css": "#id {
     background: white;
 }",
   "with-broken-sourcemap.js": "function meaningOfLife(){throw new Error(42)}
 //# sourceMappingURL=https://example.com/with-broken-sourcemap.map",
-  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"0\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
+  "with-broken-sourcemap.map": "{\\"version\\":3,\\"sources\\":[\\"with-broken-sourcemap.js\\"],\\"names\\":[\\"meaningOfLife\\",\\"Error\\"],\\"mappings\\":\\"AAAA,SAASA,gBAEP,MAAM,IAAIC,MADa\\",\\"file\\":\\"with-broken-sourcemap.js\\"}",
 }
 `;
diff --git a/test/fixtures/multi/with-multi-sourcemap.js b/test/fixtures/multi/with-multi-sourcemap.js
new file mode 100644
index 0000000..ef80444
--- /dev/null
+++ b/test/fixtures/multi/with-multi-sourcemap.js
@@ -0,0 +1,22 @@
+/* This is my header. */
+function meaningOfLife() {
+  var thisIsALongLocal = 42;
+  throw new Error(thisIsALongLocal);
+}
+
+function boom() {
+  throw new Error('boom');
+}
+function somethingElse() {
+  throw new Error("somethign else");
+}
+
+//# sourceMappingURL=missing-sourcemap.map
+
+function fourth(){
+  throw new Error('fourth');
+}
+function third(){
+  throw new Error("oh no");
+}
+//# sourceMappingURL=with-multi-sourcemap.map
\ No newline at end of file
diff --git a/test/fixtures/multi/with-multi-sourcemap.map b/test/fixtures/multi/with-multi-sourcemap.map
new file mode 100644
index 0000000..25e6224
--- /dev/null
+++ b/test/fixtures/multi/with-multi-sourcemap.map
@@ -0,0 +1 @@
+{"version":3,"sources":["/inner/first.js","/inner/second.js","/other/fourth.js","/other/third.js"],"sourcesContent":["function meaningOfLife() {\n  var thisIsALongLocal = 42;\n  throw new Error(thisIsALongLocal);\n}\n\nfunction boom() {\n  throw new Error('boom');\n}\n","function somethingElse() {\n  throw new Error(\"somethign else\");\n}\n","\n// Hello world\n\nfunction fourth(){\n  throw new Error('fourth');\n}\n","function third(){\n  throw new Error(\"oh no\");\n}\n"],"names":[],"mappings":";AAAA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;ACPA;AACA;AACA;ACFA;AACA;AACA;AACA;AACA;AACA;ACLA;AACA;AACA;","file":"with-multi-sourcemap.js"}
\ No newline at end of file