diff --git a/src/google/protobuf/map_test.inc b/src/google/protobuf/map_test.inc
index 89f8033017..8385560d7b 100644
--- a/src/google/protobuf/map_test.inc
+++ b/src/google/protobuf/map_test.inc
@@ -2708,9 +2708,7 @@ TEST(GeneratedMapFieldTest, Proto2UnknownEnum) {
   UNITTEST::TestEnumMap to;
   EXPECT_TRUE(to.ParseFromString(data));
   EXPECT_EQ(0, to.unknown_map_field().size());
-  const UnknownFieldSet& unknown_field_set =
-      to.GetReflection()->GetUnknownFields(to);
-  EXPECT_EQ(1, unknown_field_set.field_count());
+  EXPECT_EQ(1, to.GetReflection()->GetUnknownFields(to).field_count());
   EXPECT_EQ(1, to.known_map_field().size());
   EXPECT_EQ(UNITTEST::PROTO2_MAP_ENUM_FOO, to.known_map_field().at(0));
 
@@ -2723,6 +2721,20 @@ TEST(GeneratedMapFieldTest, Proto2UnknownEnum) {
   EXPECT_EQ(UNITTEST::E_PROTO2_MAP_ENUM_FOO, from.known_map_field().at(0));
   EXPECT_EQ(1, from.unknown_map_field().size());
   EXPECT_EQ(UNITTEST::E_PROTO2_MAP_ENUM_EXTRA, from.unknown_map_field().at(0));
+
+  // Test the same behavior with the reflection based parser.
+  to.Clear();
+  const char* ptr;
+  internal::ParseContext ctx(io::CodedInputStream::GetDefaultRecursionLimit(),
+                             false, &ptr, data);
+  ptr = WireFormat::_InternalParse(&to, ptr, &ctx);
+  ASSERT_TRUE(ptr);
+  ASSERT_TRUE(ctx.EndedAtLimit());
+
+  EXPECT_EQ(0, to.unknown_map_field().size());
+  EXPECT_EQ(1, to.GetReflection()->GetUnknownFields(to).field_count());
+  EXPECT_EQ(1, to.known_map_field().size());
+  EXPECT_EQ(UNITTEST::PROTO2_MAP_ENUM_FOO, to.known_map_field().at(0));
 }
 
 TEST(GeneratedMapFieldTest, StandardWireFormat) {
diff --git a/src/google/protobuf/wire_format.cc b/src/google/protobuf/wire_format.cc
index f988a090c4..27aa64fda9 100644
--- a/src/google/protobuf/wire_format.cc
+++ b/src/google/protobuf/wire_format.cc
@@ -1030,7 +1030,25 @@ const char* WireFormat::_InternalParseAndMergeField(
         sub_message =
             reflection->MutableMessage(msg, field, ctx->data().factory);
       }
-      return ctx->ParseMessage(sub_message, ptr);
+      ptr = ctx->ParseMessage(sub_message, ptr);
+
+      // For map entries, if the value is an unknown enum we have to push it
+      // into the unknown field set and remove it from the list.
+      if (ptr != nullptr && field->is_map()) {
+        auto* value_field = field->message_type()->map_value();
+        auto* enum_type = value_field->enum_type();
+        if (enum_type != nullptr &&
+            !internal::cpp::HasPreservingUnknownEnumSemantics(value_field) &&
+            enum_type->FindValueByNumber(
+                sub_message->GetReflection()->GetEnumValue(
+                    *sub_message, value_field)) == nullptr) {
+          reflection->MutableUnknownFields(msg)->AddLengthDelimited(
+              field->number(), sub_message->SerializeAsString());
+          reflection->RemoveLast(msg, field);
+        }
+      }
+
+      return ptr;
     }
   }