diff --git a/src/core/jsonschema/bundle.cc b/src/core/jsonschema/bundle.cc
index 2a1361042..cb6eb7239 100644
--- a/src/core/jsonschema/bundle.cc
+++ b/src/core/jsonschema/bundle.cc
@@ -454,10 +454,14 @@ auto bundle(JSON &schema, const SchemaWalker &walker,
   if (ref_overrides_adjacent_keywords(schema_base_dialect.value()) &&
       schema.is_object() && schema.defines("$ref")) {
     if (schema.size() == 1) {
+      const auto is_draft3{schema_base_dialect.value() ==
+                               SchemaBaseDialect::JSON_Schema_Draft_3 ||
+                           schema_base_dialect.value() ==
+                               SchemaBaseDialect::JSON_Schema_Draft_3_Hyper};
       auto branches{JSON::make_array()};
       branches.push_back(schema);
       schema.at("$ref").into(std::move(branches));
-      schema.rename("$ref", "allOf");
+      schema.rename("$ref", is_draft3 ? "extends" : "allOf");
     } else {
       throw SchemaError(
           "Cannot bundle a JSON Schema Draft 7 or older with a top-level "
diff --git a/src/core/jsonschema/helpers.h b/src/core/jsonschema/helpers.h
index ad2635552..b3ca84fa2 100644
--- a/src/core/jsonschema/helpers.h
+++ b/src/core/jsonschema/helpers.h
@@ -48,9 +48,9 @@ inline auto definitions_keyword(const SchemaBaseDialect base_dialect)
     case SchemaBaseDialect::JSON_Schema_Draft_6_Hyper:
     case SchemaBaseDialect::JSON_Schema_Draft_4:
     case SchemaBaseDialect::JSON_Schema_Draft_4_Hyper:
-      return "definitions";
     case SchemaBaseDialect::JSON_Schema_Draft_3:
     case SchemaBaseDialect::JSON_Schema_Draft_3_Hyper:
+      return "definitions";
     case SchemaBaseDialect::JSON_Schema_Draft_2_Hyper:
     case SchemaBaseDialect::JSON_Schema_Draft_1_Hyper:
     case SchemaBaseDialect::JSON_Schema_Draft_0_Hyper:
diff --git a/src/core/jsonschema/known_walker.cc b/src/core/jsonschema/known_walker.cc
index b31b23b53..f439eb5d4 100644
--- a/src/core/jsonschema/known_walker.cc
+++ b/src/core/jsonschema/known_walker.cc
@@ -154,6 +154,10 @@ auto handle_definitions(const Vocabularies &vocabularies)
                                      LocationMembers, "$ref")
   CHECK_VOCABULARY_WITH_DEPENDENCIES(Known::JSON_Schema_Draft_4_Hyper, {},
                                      LocationMembers, "$ref")
+  CHECK_VOCABULARY_WITH_DEPENDENCIES(Known::JSON_Schema_Draft_3, {},
+                                     LocationMembers, "$ref")
+  CHECK_VOCABULARY_WITH_DEPENDENCIES(Known::JSON_Schema_Draft_3_Hyper, {},
+                                     LocationMembers, "$ref")
   return UNKNOWN_RESULT;
 }
 
diff --git a/test/jsonschema/jsonschema_bundle_draft3_test.cc b/test/jsonschema/jsonschema_bundle_draft3_test.cc
index 52a891971..d4bfacaef 100644
--- a/test/jsonschema/jsonschema_bundle_draft3_test.cc
+++ b/test/jsonschema/jsonschema_bundle_draft3_test.cc
@@ -14,6 +14,32 @@ static auto test_resolver(std::string_view identifier)
       "id": "https://www.sourcemeta.com/test-1",
       "type": "string"
     })JSON");
+  } else if (identifier == "https://www.sourcemeta.com/test-2") {
+    return sourcemeta::core::parse_json(R"JSON({
+      "$schema": "http://json-schema.org/draft-03/schema#",
+      "id": "https://www.sourcemeta.com/test-2",
+      "extends": { "$ref": "test-3" }
+    })JSON");
+  } else if (identifier == "https://www.sourcemeta.com/test-3") {
+    return sourcemeta::core::parse_json(R"JSON({
+      "$schema": "http://json-schema.org/draft-03/schema#",
+      "id": "https://www.sourcemeta.com/test-3",
+      "extends": { "$ref": "test-1" }
+    })JSON");
+  } else if (identifier == "https://www.sourcemeta.com/test-4") {
+    return sourcemeta::core::parse_json(R"JSON({
+      "$schema": "http://json-schema.org/draft-03/schema#",
+      "id": "https://www.sourcemeta.com/test-4",
+      "type": "boolean"
+    })JSON");
+  } else if (identifier == "https://www.sourcemeta.com/recursive") {
+    return sourcemeta::core::parse_json(R"JSON({
+      "$schema": "http://json-schema.org/draft-03/schema#",
+      "id": "https://www.sourcemeta.com/recursive",
+      "properties": {
+        "foo": { "$ref": "#" }
+      }
+    })JSON");
   } else {
     return sourcemeta::core::schema_resolver(identifier);
   }
@@ -58,7 +84,272 @@ TEST(JSONSchema_bundle_draft3, simple_bundling) {
     }
   })JSON");
 
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "test": { "$ref": "https://www.sourcemeta.com/test-1" }
+    },
+    "definitions": {
+      "https://www.sourcemeta.com/test-1": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-1",
+        "type": "string"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(JSONSchema_bundle_draft3, simple_with_id) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "foo": { "$ref": "https://www.sourcemeta.com/test-1" },
+      "bar": {
+        "id": "https://www.sourcemeta.com",
+        "extends": { "$ref": "test-2" }
+      }
+    }
+  })JSON");
+
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "foo": { "$ref": "https://www.sourcemeta.com/test-1" },
+      "bar": {
+        "id": "https://www.sourcemeta.com",
+        "extends": { "$ref": "test-2" }
+      }
+    },
+    "definitions": {
+      "https://www.sourcemeta.com/test-1": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-1",
+        "type": "string"
+      },
+      "https://www.sourcemeta.com/test-2": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-2",
+        "extends": { "$ref": "test-3" }
+      },
+      "https://www.sourcemeta.com/test-3": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-3",
+        "extends": { "$ref": "test-1" }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(JSONSchema_bundle_draft3, schema_not_found) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "foo": { "$ref": "https://www.sourcemeta.com/xxx" }
+    }
+  })JSON");
+
   EXPECT_THROW(sourcemeta::core::bundle(
                    document, sourcemeta::core::schema_walker, test_resolver),
-               sourcemeta::core::SchemaError);
+               sourcemeta::core::SchemaResolutionError);
+}
+
+TEST(JSONSchema_bundle_draft3, idempotency) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "test": { "$ref": "https://www.sourcemeta.com/test-2" }
+    }
+  })JSON");
+
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "test": { "$ref": "https://www.sourcemeta.com/test-2" }
+    },
+    "definitions": {
+      "https://www.sourcemeta.com/test-1": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-1",
+        "type": "string"
+      },
+      "https://www.sourcemeta.com/test-2": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-2",
+        "extends": { "$ref": "test-3" }
+      },
+      "https://www.sourcemeta.com/test-3": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-3",
+        "extends": { "$ref": "test-1" }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(JSONSchema_bundle_draft3, pre_embedded) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "test": { "$ref": "https://www.sourcemeta.com/test-2" }
+    },
+    "definitions": {
+      "already-embedded": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-1",
+        "type": "string"
+      }
+    }
+  })JSON");
+
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "test": { "$ref": "https://www.sourcemeta.com/test-2" }
+    },
+    "definitions": {
+      "already-embedded": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-1",
+        "type": "string"
+      },
+      "https://www.sourcemeta.com/test-2": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-2",
+        "extends": { "$ref": "test-3" }
+      },
+      "https://www.sourcemeta.com/test-3": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-3",
+        "extends": { "$ref": "test-1" }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(JSONSchema_bundle_draft3, taken_definitions_entry) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "test": { "$ref": "https://www.sourcemeta.com/test-1" },
+      "extra": { "$ref": "https://www.sourcemeta.com/test-4" }
+    },
+    "definitions": {
+      "https://www.sourcemeta.com/test-1": { "type": "object" },
+      "https://www.sourcemeta.com/test-4": { "type": "object" },
+      "https://www.sourcemeta.com/test-4/x": { "type": "object" },
+      "https://www.sourcemeta.com/test-4/x/x": { "type": "object" }
+    }
+  })JSON");
+
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "id": "https://example.com",
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "test": { "$ref": "https://www.sourcemeta.com/test-1" },
+      "extra": { "$ref": "https://www.sourcemeta.com/test-4" }
+    },
+    "definitions": {
+      "https://www.sourcemeta.com/test-1": { "type": "object" },
+      "https://www.sourcemeta.com/test-1/x": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-1",
+        "type": "string"
+      },
+      "https://www.sourcemeta.com/test-4": { "type": "object" },
+      "https://www.sourcemeta.com/test-4/x": { "type": "object" },
+      "https://www.sourcemeta.com/test-4/x/x": { "type": "object" },
+      "https://www.sourcemeta.com/test-4/x/x/x": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-4",
+        "type": "boolean"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(JSONSchema_bundle_draft3, recursive) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "extends": { "$ref": "https://www.sourcemeta.com/recursive" }
+  })JSON");
+
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "extends": { "$ref": "https://www.sourcemeta.com/recursive" },
+    "definitions": {
+      "https://www.sourcemeta.com/recursive": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/recursive",
+        "properties": {
+          "foo": { "$ref": "#" }
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(JSONSchema_bundle_draft3, standalone_ref_with_default_dialect) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$ref": "https://www.sourcemeta.com/test-1"
+  })JSON");
+
+  sourcemeta::core::bundle(document, sourcemeta::core::schema_walker,
+                           test_resolver,
+                           "http://json-schema.org/draft-03/schema#");
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "extends": [ { "$ref": "https://www.sourcemeta.com/test-1" } ],
+    "definitions": {
+      "https://www.sourcemeta.com/test-1": {
+        "$schema": "http://json-schema.org/draft-03/schema#",
+        "id": "https://www.sourcemeta.com/test-1",
+        "type": "string"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
 }
diff --git a/test/jsonschema/jsonschema_frame_draft3_test.cc b/test/jsonschema/jsonschema_frame_draft3_test.cc
index 182048cb9..08d8c8fec 100644
--- a/test/jsonschema/jsonschema_frame_draft3_test.cc
+++ b/test/jsonschema/jsonschema_frame_draft3_test.cc
@@ -942,3 +942,116 @@ TEST(JSONSchema_frame_draft3, id_fragment_invalid_whitespace) {
     FAIL();
   }
 }
+
+TEST(JSONSchema_frame_draft3, definitions_subschemas) {
+  const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "definitions": {
+      "string": { "type": "string" }
+    }
+  })JSON");
+
+  sourcemeta::core::SchemaFrame frame{
+      sourcemeta::core::SchemaFrame::Mode::References};
+  frame.analyse(document, sourcemeta::core::schema_walker,
+                sourcemeta::core::schema_resolver);
+
+  EXPECT_EQ(frame.locations().size(), 5);
+
+  EXPECT_ANONYMOUS_FRAME_STATIC_SUBSCHEMA(
+      frame, "", "", "http://json-schema.org/draft-03/schema#",
+      JSON_Schema_Draft_3, std::nullopt, false, false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/$schema", "/$schema", "http://json-schema.org/draft-03/schema#",
+      JSON_Schema_Draft_3, "", false, false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/definitions", "/definitions",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3, "", false,
+      false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_SUBSCHEMA(
+      frame, "#/definitions/string", "/definitions/string",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3, "", false,
+      true);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/definitions/string/type", "/definitions/string/type",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3,
+      "/definitions/string", false, true);
+
+  EXPECT_EQ(frame.references().size(), 1);
+
+  EXPECT_STATIC_REFERENCE(
+      frame, "/$schema", "http://json-schema.org/draft-03/schema",
+      "http://json-schema.org/draft-03/schema", std::nullopt,
+      "http://json-schema.org/draft-03/schema#");
+
+  EXPECT_FRAME_LOCATION_REACHABLE(frame, Static, "", frame.root());
+  EXPECT_FRAME_LOCATION_NON_REACHABLE(frame, Static, "#/definitions/string",
+                                      frame.root());
+  EXPECT_FRAME_LOCATION_REACHABLE(frame, Static, "#/definitions/string",
+                                  "#/definitions/string");
+}
+
+TEST(JSONSchema_frame_draft3, ref_into_definitions) {
+  const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-03/schema#",
+    "properties": {
+      "foo": { "$ref": "#/definitions/string" }
+    },
+    "definitions": {
+      "string": { "type": "string" }
+    }
+  })JSON");
+
+  sourcemeta::core::SchemaFrame frame{
+      sourcemeta::core::SchemaFrame::Mode::References};
+  frame.analyse(document, sourcemeta::core::schema_walker,
+                sourcemeta::core::schema_resolver);
+
+  EXPECT_EQ(frame.locations().size(), 8);
+
+  EXPECT_ANONYMOUS_FRAME_STATIC_SUBSCHEMA(
+      frame, "", "", "http://json-schema.org/draft-03/schema#",
+      JSON_Schema_Draft_3, std::nullopt, false, false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/$schema", "/$schema", "http://json-schema.org/draft-03/schema#",
+      JSON_Schema_Draft_3, "", false, false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/properties", "/properties",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3, "", false,
+      false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_SUBSCHEMA(
+      frame, "#/properties/foo", "/properties/foo",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3, "", false,
+      false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/properties/foo/$ref", "/properties/foo/$ref",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3,
+      "/properties/foo", false, false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/definitions", "/definitions",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3, "", false,
+      false);
+  EXPECT_ANONYMOUS_FRAME_STATIC_SUBSCHEMA(
+      frame, "#/definitions/string", "/definitions/string",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3, "", false,
+      true);
+  EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
+      frame, "#/definitions/string/type", "/definitions/string/type",
+      "http://json-schema.org/draft-03/schema#", JSON_Schema_Draft_3,
+      "/definitions/string", false, true);
+
+  EXPECT_EQ(frame.references().size(), 2);
+
+  EXPECT_STATIC_REFERENCE(
+      frame, "/$schema", "http://json-schema.org/draft-03/schema",
+      "http://json-schema.org/draft-03/schema", std::nullopt,
+      "http://json-schema.org/draft-03/schema#");
+  EXPECT_STATIC_REFERENCE(frame, "/properties/foo/$ref", "#/definitions/string",
+                          "", "/definitions/string", "#/definitions/string");
+
+  EXPECT_FRAME_LOCATION_REACHABLE(frame, Static, "", frame.root());
+  EXPECT_FRAME_LOCATION_REACHABLE(frame, Static, "#/properties/foo",
+                                  frame.root());
+  EXPECT_FRAME_LOCATION_REACHABLE(frame, Static, "#/definitions/string",
+                                  frame.root());
+}
diff --git a/test/jsonschema/jsonschema_walker_draft3_test.cc b/test/jsonschema/jsonschema_walker_draft3_test.cc
index db399714d..2b981cdb7 100644
--- a/test/jsonschema/jsonschema_walker_draft3_test.cc
+++ b/test/jsonschema/jsonschema_walker_draft3_test.cc
@@ -48,6 +48,31 @@ TEST(JSONSchema_walker_draft3, ref) {
   EXPECT_TRUE(result.instances.none());
 }
 
+TEST(JSONSchema_walker_draft3, definitions) {
+  using namespace sourcemeta::core;
+  const auto &result{schema_walker("definitions", VOCABULARIES_DRAFT3)};
+  EXPECT_EQ(result.type, SchemaKeywordType::LocationMembers);
+  EXPECT_TRUE(result.vocabulary.has_value());
+  EXPECT_VOCABULARY_KNOWN(result.vocabulary.value(), JSON_Schema_Draft_3);
+  const std::unordered_set<std::string_view> expected{"$ref"};
+  EXPECT_EQ(result.dependencies, expected);
+  EXPECT_TRUE(result.order_dependencies.empty());
+  EXPECT_TRUE(result.instances.none());
+}
+
+TEST(JSONSchema_walker_draft3_hyperschema, definitions) {
+  using namespace sourcemeta::core;
+  const auto &result{
+      schema_walker("definitions", VOCABULARIES_DRAFT3_HYPERSCHEMA)};
+  EXPECT_EQ(result.type, SchemaKeywordType::LocationMembers);
+  EXPECT_TRUE(result.vocabulary.has_value());
+  EXPECT_VOCABULARY_KNOWN(result.vocabulary.value(), JSON_Schema_Draft_3_Hyper);
+  const std::unordered_set<std::string_view> expected{"$ref"};
+  EXPECT_EQ(result.dependencies, expected);
+  EXPECT_TRUE(result.order_dependencies.empty());
+  EXPECT_TRUE(result.instances.none());
+}
+
 TEST(JSONSchema_walker_draft3, items) {
   using namespace sourcemeta::core;
   const auto &result{schema_walker("items", VOCABULARIES_DRAFT3)};