Index: generic/nsf.c
===================================================================
diff -u -re4500c77b2bdbb0733a1503d765be84f15509be3 -rdb831678bc92ce4e39bf4ff303f32491a3c4f9d9
--- generic/nsf.c	(.../nsf.c)	(revision e4500c77b2bdbb0733a1503d765be84f15509be3)
+++ generic/nsf.c	(.../nsf.c)	(revision db831678bc92ce4e39bf4ff303f32491a3c4f9d9)
@@ -13087,13 +13087,14 @@
   assert(outObjPtr); // autoadded
 
   if (unlikely(pPtr->converterArg != NULL)) {
-    Tcl_Obj *objv[3];
+    Tcl_Obj *objv[4];
     /*fprintf(stderr, "ConvertToTclobj %s (must be %s)\n", ObjStr(objPtr), ObjStr(pPtr->converterArg));*/
 
     objv[1] = pPtr->converterArg;
-    objv[2] = objPtr;
+    objv[2] = NsfGlobalObjs[NSF_OPTION_STRICT];
+    objv[3] = objPtr;
 
-    result = NsfCallCommand(interp, NSF_IS, 3, objv);
+    result = NsfCallCommand(interp, NSF_STRING_IS, 4, objv);
     if (likely(result == TCL_OK)) {
       int success;
       Tcl_GetIntFromObj(interp, Tcl_GetObjResult(interp), &success);