Index: generic/nsf.c
===================================================================
diff -u -N -re89a635d134e85db66c3e7059ec81817b6b36ea5 -re3150993c2a30e0197fd3caabb1859e4bd66df62
--- generic/nsf.c	(.../nsf.c)	(revision e89a635d134e85db66c3e7059ec81817b6b36ea5)
+++ generic/nsf.c	(.../nsf.c)	(revision e3150993c2a30e0197fd3caabb1859e4bd66df62)
@@ -32434,10 +32434,16 @@
                          NsfMethodName(objv[0]));
   }
 
-  result = TclObjGetFrame(interp, objv[1], &requestedFramePtr);
-  if (unlikely(result == -1)) {
-    return TCL_ERROR;
+
+  if (objc == 2) {
+    result = 0;
+  } else {
+    result = TclObjGetFrame(interp, objv[1], &requestedFramePtr);
+    if (unlikely(result == -1)) {
+      return TCL_ERROR;
+    }
   }
+  
   objc -= result + 1;
   if (objc == 0) {
     goto wrongArgs;