diff --git a/src/debug.cc b/src/debug.cc
index 4c53e19..c2d324e 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -753,8 +753,8 @@
   Handle<String> source_code =
       isolate->bootstrapper()->NativesSourceLookup(index);
   Vector<const char> name = Natives::GetScriptName(index);
-  Handle<String> script_name = factory->NewStringFromAscii(name);
-  ASSERT(!script_name.is_null());
+  Handle<String> script_name =
+      factory->NewStringFromAscii(name).ToHandleChecked();
   Handle<Context> context = isolate->native_context();
 
   // Compile the script.