Index: generic/nsf.c
===================================================================
diff -u -rc24b68646f2b5bc897704b212a10fdd35fa5c33a -rd9c458b8e9f74e94829dec92c814894e8cff0577
--- generic/nsf.c	(.../nsf.c)	(revision c24b68646f2b5bc897704b212a10fdd35fa5c33a)
+++ generic/nsf.c	(.../nsf.c)	(revision d9c458b8e9f74e94829dec92c814894e8cff0577)
@@ -8612,7 +8612,7 @@
  *
  *----------------------------------------------------------------------
  */
-static NsfCmdList * SeekCurrent(Tcl_Command cmd, register NsfCmdList *cmdListPtr);
+static NsfCmdList * SeekCurrent(Tcl_Command cmd, register NsfCmdList *cmdListPtr) nonnull(2);
 
 static NsfCmdList *
 SeekCurrent(Tcl_Command cmd, register NsfCmdList *cmdListPtr) {
@@ -8711,6 +8711,10 @@
   /* ensure that the mixin order is valid */
   assert(object->flags & NSF_MIXIN_ORDER_VALID);
 
+  if (object->mixinOrder == NULL) {
+    return TCL_OK;
+  }
+
   cmdList = SeekCurrent(object->mixinStack->currentCmdPtr, object->mixinOrder);
   RUNTIME_STATE(interp)->currentMixinCmdPtr = cmdList ? cmdList->cmdPtr : NULL;