diff --git a/src/tools/type-generator/main.cpp b/src/tools/type-generator/main.cpp
index 2d436b3c93..887b5117e9 100644
--- a/src/tools/type-generator/main.cpp
+++ b/src/tools/type-generator/main.cpp
@@ -1839,6 +1839,7 @@ writeMap(Output* out, Object* type)
     Object* m = it.next();
 
     if (it.sawSuperclassBoundary) {
+      it.sawSuperclassBoundary = false;
       out->write("Type_pad, ");
     }