diff --git a/Libraries/LibHTML/CodeGenerators/Generate_CSS_PropertyID_cpp/Generate_CSS_PropertyID_cpp.cpp b/Libraries/LibHTML/CodeGenerators/Generate_CSS_PropertyID_cpp/Generate_CSS_PropertyID_cpp.cpp
index 7c1e7734e0..23b8ae2e65 100644
--- a/Libraries/LibHTML/CodeGenerators/Generate_CSS_PropertyID_cpp/Generate_CSS_PropertyID_cpp.cpp
+++ b/Libraries/LibHTML/CodeGenerators/Generate_CSS_PropertyID_cpp/Generate_CSS_PropertyID_cpp.cpp
@@ -56,8 +56,7 @@ int main(int argc, char** argv)
         dbg() << "        return \"" << name << "\";";
     });
     dbg() << "    default:";
-    dbg() << "        ASSERT_NOT_REACHED();";
-    dbg() << "        return nullptr;";
+    dbg() << "        return \"(invalid CSS::PropertyID)\";";
     dbg() << "    }";
     dbg() << "}";
     dbg() << "}";