diff --git a/src/google/protobuf/compiler/parser.cc b/src/google/protobuf/compiler/parser.cc
index 7ff4cb2a8a..6620085c79 100644
--- a/src/google/protobuf/compiler/parser.cc
+++ b/src/google/protobuf/compiler/parser.cc
@@ -571,6 +571,26 @@ void Parser::SkipRestOfBlock() {
 
 // ===================================================================
 
+bool Parser::ValidateMessage(const DescriptorProto* proto) {
+  for (int i = 0; i < proto->options().uninterpreted_option_size(); i++) {
+    const UninterpretedOption& option =
+        proto->options().uninterpreted_option(i);
+    if (option.name_size() > 0 && !option.name(0).is_extension() &&
+        option.name(0).name_part() == "map_entry") {
+      int line = -1, col = 0;  // indicates line and column not known
+      if (source_location_table_ != nullptr) {
+        source_location_table_->Find(
+            &option, DescriptorPool::ErrorCollector::OPTION_NAME, &line, &col);
+      }
+      RecordError(line, col,
+                  "map_entry should not be set explicitly. "
+                  "Use map<KeyType, ValueType> instead.");
+      return false;
+    }
+  }
+  return true;
+}
+
 bool Parser::ValidateEnum(const EnumDescriptorProto* proto) {
   bool has_allow_alias = false;
   bool allow_alias = false;
@@ -866,6 +886,7 @@ bool IsMessageSetWireFormatMessage(const DescriptorProto& message) {
   for (int i = 0; i < options.uninterpreted_option_size(); ++i) {
     const UninterpretedOption& uninterpreted = options.uninterpreted_option(i);
     if (uninterpreted.name_size() == 1 &&
+        !uninterpreted.name(0).is_extension() &&
         uninterpreted.name(0).name_part() == "message_set_wire_format" &&
         uninterpreted.identifier_value() == "true") {
       return true;
@@ -930,6 +951,9 @@ bool Parser::ParseMessageBlock(DescriptorProto* message,
   if (message->reserved_range_size() > 0) {
     AdjustReservedRangesWithMaxEndNumber(message);
   }
+
+  DO(ValidateMessage(message));
+
   return true;
 }
 
diff --git a/src/google/protobuf/compiler/parser.h b/src/google/protobuf/compiler/parser.h
index 4808be3b73..04028c192a 100644
--- a/src/google/protobuf/compiler/parser.h
+++ b/src/google/protobuf/compiler/parser.h
@@ -540,6 +540,7 @@ class PROTOBUF_EXPORT Parser {
     return syntax_identifier_ == "proto3";
   }
 
+  bool ValidateMessage(const DescriptorProto* proto);
   bool ValidateEnum(const EnumDescriptorProto* proto);
 
   // =================================================================
diff --git a/src/google/protobuf/compiler/parser_unittest.cc b/src/google/protobuf/compiler/parser_unittest.cc
index 4c9763b2aa..31a0c78b82 100644
--- a/src/google/protobuf/compiler/parser_unittest.cc
+++ b/src/google/protobuf/compiler/parser_unittest.cc
@@ -171,6 +171,8 @@ class ParserTest : public testing::Test {
   // input.
   void ExpectHasEarlyExitErrors(const char* text, const char* expected_errors) {
     SetupParser(text);
+    SourceLocationTable source_locations;
+    parser_->RecordSourceLocationsTo(&source_locations);
     FileDescriptorProto file;
     EXPECT_FALSE(parser_->Parse(input_.get(), &file));
     EXPECT_EQ(expected_errors, error_collector_.text_);
@@ -2357,7 +2359,7 @@ TEST_F(ParserValidationErrorTest, EnumReservedRangeError) {
 }
 
 TEST_F(ParserValidationErrorTest, ExplicitlyMapEntryError) {
-  ExpectHasValidationErrors(
+  ExpectHasErrors(
       "message Foo {\n"
       "  message ValueEntry {\n"
       "    option map_entry = true;\n"
@@ -2365,9 +2367,8 @@ TEST_F(ParserValidationErrorTest, ExplicitlyMapEntryError) {
       "    optional int32 value = 2;\n"
       "    extensions 99 to 999;\n"
       "  }\n"
-      "  repeated ValueEntry value = 1;\n"
       "}",
-      "7:11: map_entry should not be set explicitly. Use "
+      "2:11: map_entry should not be set explicitly. Use "
       "map<KeyType, ValueType> instead.\n");
 }