diff --git a/Libraries/LibIDL/IDLParser.cpp b/Libraries/LibIDL/IDLParser.cpp
index 3d6ddb087d8..544b36eac6d 100644
--- a/Libraries/LibIDL/IDLParser.cpp
+++ b/Libraries/LibIDL/IDLParser.cpp
@@ -813,13 +813,14 @@ void Parser::parse_interface(Interface& interface)
     consume_whitespace();
 }
 
-void Parser::parse_partial_interface(Interface& parent)
+void Parser::parse_partial_interface(HashMap<ByteString, ByteString> extended_attributes, Interface& parent)
 {
     assert_string("partial"sv);
     consume_whitespace();
     assert_string("interface"sv);
 
     auto partial_interface = make<Interface>();
+    partial_interface->extended_attributes = move(extended_attributes);
     parse_interface(*partial_interface);
     parent.partial_interfaces.append(move(partial_interface));
 }
@@ -1063,7 +1064,7 @@ void Parser::parse_non_interface_entities(bool allow_interface, Interface& inter
         } else if (lexer.next_is("typedef")) {
             parse_typedef(interface);
         } else if (lexer.next_is("partial interface"sv)) {
-            parse_partial_interface(interface);
+            parse_partial_interface(extended_attributes, interface);
         } else if (lexer.next_is("interface mixin")) {
             parse_interface_mixin(interface);
         } else if (lexer.next_is("callback")) {
diff --git a/Libraries/LibIDL/IDLParser.h b/Libraries/LibIDL/IDLParser.h
index 3b2a6e818e7..16ae1998da6 100644
--- a/Libraries/LibIDL/IDLParser.h
+++ b/Libraries/LibIDL/IDLParser.h
@@ -45,7 +45,7 @@ private:
     HashMap<ByteString, ByteString> parse_extended_attributes();
     void parse_attribute(HashMap<ByteString, ByteString>& extended_attributes, Interface&, IsStatic is_static = IsStatic::No);
     void parse_interface(Interface&);
-    void parse_partial_interface(Interface& parent);
+    void parse_partial_interface(HashMap<ByteString, ByteString> extended_attributes, Interface& parent);
     void parse_namespace(Interface&);
     void parse_non_interface_entities(bool allow_interface, Interface&);
     void parse_enumeration(HashMap<ByteString, ByteString>, Interface&);
diff --git a/Libraries/LibIDL/Types.cpp b/Libraries/LibIDL/Types.cpp
index aaaf21e86de..56b168d1fe9 100644
--- a/Libraries/LibIDL/Types.cpp
+++ b/Libraries/LibIDL/Types.cpp
@@ -307,11 +307,39 @@ void EffectiveOverloadSet::remove_all_other_entries()
 
 void Interface::extend_with_partial_interface(Interface const& partial)
 {
-    attributes.extend(partial.attributes);
-    static_attributes.extend(partial.static_attributes);
+    for (auto const& attribute : partial.attributes) {
+        auto attribute_copy = attribute;
+        for (auto const& [key, value] : partial.extended_attributes) {
+            attribute_copy.extended_attributes.set(key, value);
+        }
+        attributes.append(move(attribute_copy));
+    }
+
+    for (auto const& static_attribute : partial.static_attributes) {
+        auto static_attribute_copy = static_attribute;
+        for (auto const& [key, value] : partial.extended_attributes) {
+            static_attribute_copy.extended_attributes.set(key, value);
+        }
+        static_attributes.append(move(static_attribute_copy));
+    }
+
     constants.extend(partial.constants);
-    functions.extend(partial.functions);
-    static_functions.extend(partial.static_functions);
+
+    for (auto const& function : partial.functions) {
+        auto function_copy = function;
+        for (auto const& [key, value] : partial.extended_attributes) {
+            function_copy.extended_attributes.set(key, value);
+        }
+        functions.append(move(function_copy));
+    }
+
+    for (auto const& static_function : partial.static_functions) {
+        auto static_function_copy = static_function;
+        for (auto const& [key, value] : partial.extended_attributes) {
+            static_function_copy.extended_attributes.set(key, value);
+        }
+        static_functions.append(move(static_function_copy));
+    }
 }
 
 }