diff --git a/ranges/subset.js b/ranges/subset.js
index a9498323..45efaeab 100644
--- a/ranges/subset.js
+++ b/ranges/subset.js
@@ -124,11 +124,15 @@ const simpleSubset = (sub, dom, options) => {
 
   // will iterate one or zero times
   for (const eq of eqSet) {
-    if (gt && !satisfies(eq, String(gt), options)) {
+    // test the eq version against the raw bound comparator; going through
+    // satisfies() rebuilds a full Range and re-applies prerelease gating, which
+    // wrongly rejects a prerelease eq against a plain bound of another tuple
+    // (the same fix PR #867 applied to the dom-side checks below)
+    if (gt && !gt.test(eq)) {
       return null
     }
 
-    if (lt && !satisfies(eq, String(lt), options)) {
+    if (lt && !lt.test(eq)) {
       return null
     }
 
diff --git a/test/ranges/subset.js b/test/ranges/subset.js
index c6de3570..a0781be1 100644
--- a/test/ranges/subset.js
+++ b/test/ranges/subset.js
@@ -13,6 +13,11 @@ const cases = [
   ['1.2.3', '>1.2.0', true],
   ['1.2.3 2.3.4 || 2.3.4', '3', false],
   ['^1.2.3-pre.0', '1.x', false],
+  // a prerelease `=` comparator combined with a bound of a different tuple must
+  // not be treated as a null set (subset false-positive): 1.1.2-alpha is in sub
+  // but not in dom, so sub is not a subset of dom
+  ['=1.1.2-alpha <3.1.0', '<1.0.0', false],
+  ['<3.1.0-0 1.1.2-alpha', '~2.0', false],
   ['^1.2.3-pre.0', '1.x', true, { includePrerelease: true }],
   ['>2 <1', '3', true],
   ['1 || 2 || 3', '>=1.0.0', true],