diff --git a/engine/src/flutter/lib/ui/ui_dart_state.cc b/engine/src/flutter/lib/ui/ui_dart_state.cc
index de40bc9b4f..ef6796fc47 100644
--- a/engine/src/flutter/lib/ui/ui_dart_state.cc
+++ b/engine/src/flutter/lib/ui/ui_dart_state.cc
@@ -34,12 +34,11 @@ UIDartState* UIDartState::CreateForChildIsolate() {
 }
 
 void UIDartState::DidSetIsolate() {
+  FTL_DCHECK(!debug_name_prefix_.empty());
   main_port_ = Dart_GetMainPortId();
-  tonic::DartApiScope api_scope;
-  Dart_Handle debug_name = Dart_DebugName();
-  if (Dart_IsString(debug_name)) {
-    debug_name_ = tonic::StdStringFromDart(debug_name);
-  }
+  std::ostringstream debug_name;
+  debug_name << debug_name_prefix_ << "$main-" << main_port_;
+  debug_name_ = debug_name.str();
 }
 
 UIDartState* UIDartState::Current() {
@@ -50,8 +49,13 @@ void UIDartState::set_font_selector(PassRefPtr<FontSelector> selector) {
   font_selector_ = selector;
 }
 
+
 PassRefPtr<FontSelector> UIDartState::font_selector() {
   return font_selector_;
 }
 
+void UIDartState::set_debug_name_prefix(const std::string& debug_name_prefix) {
+  debug_name_prefix_ = debug_name_prefix;
+}
+
 }  // namespace blink
diff --git a/engine/src/flutter/lib/ui/ui_dart_state.h b/engine/src/flutter/lib/ui/ui_dart_state.h
index 23b3eee4ef..99af0a432d 100644
--- a/engine/src/flutter/lib/ui/ui_dart_state.h
+++ b/engine/src/flutter/lib/ui/ui_dart_state.h
@@ -39,6 +39,7 @@ class UIDartState : public tonic::DartState {
   const std::string& debug_name() const { return debug_name_; }
   Window* window() const { return window_.get(); }
 
+  void set_debug_name_prefix(const std::string& debug_name_prefix);
   void set_font_selector(PassRefPtr<FontSelector> selector);
   PassRefPtr<FontSelector> font_selector();
 
@@ -47,6 +48,7 @@ class UIDartState : public tonic::DartState {
 
   IsolateClient* isolate_client_;
   Dart_Port main_port_;
+  std::string debug_name_prefix_;
   std::string debug_name_;
   std::unique_ptr<Window> window_;
   RefPtr<FontSelector> font_selector_;
diff --git a/engine/src/flutter/runtime/dart_controller.cc b/engine/src/flutter/runtime/dart_controller.cc
index 1f298ca5ea..d5a15b30e4 100644
--- a/engine/src/flutter/runtime/dart_controller.cc
+++ b/engine/src/flutter/runtime/dart_controller.cc
@@ -196,6 +196,7 @@ void DartController::CreateIsolateFor(const std::string& script_uri,
 
   Dart_SetShouldPauseOnStart(Settings::Get().start_paused);
 
+  ui_dart_state_->set_debug_name_prefix(script_uri);
   ui_dart_state_->SetIsolate(isolate);
   FTL_CHECK(!LogIfError(
       Dart_SetLibraryTagHandler(tonic::DartState::HandleLibraryTag)));