diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 45897817a56051..31f744aaf6e9e2 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -583,8 +583,12 @@ Tkapp_New(const char *screenName, const char *className,
 
     v->interp = Tcl_CreateInterp();
     v->wantobjects = wantobjects;
+#if TCL_MAJOR_VERSION >= 9
+    v->threaded = 1;
+#else
     v->threaded = Tcl_GetVar2Ex(v->interp, "tcl_platform", "threaded",
                                 TCL_GLOBAL_ONLY) != NULL;
+#endif
     v->thread_id = Tcl_GetCurrentThread();
     v->dispatching = 0;
     v->trace = NULL;