@@ -310,10 +310,19 @@
 	#   string    (TCL_DYNAMIC char*)
 	#   dstring   (TCL_DYNAMIC char*)
 	#   vstring   (TCL_VOLATILE char*)
 	#   default   (Tcl_Obj*)
 	#   wide
+	switch -- $rtype {
+		void - ok - int - long - float - double - wide {}
+		default {
+			append cbody "  if (rv == NULL) {\n"
+			append cbody "    return(TCL_ERROR);\n"
+			append cbody "  }\n"
+		}
+	}
+
 	switch -- $rtype {
 		void           { }
 		ok             { append cbody "  return rv;" "\n" }
 		int            { append cbody "  Tcl_SetIntObj(Tcl_GetObjResult(ip), rv);" "\n" }
 		long           { append cbody "  Tcl_SetLongObj(Tcl_GetObjResult(ip), rv);" "\n" }