Index: src/tclx/src/tclxstr.c
--- src/tclx/src/tclxstr.c.orig
+++ src/tclx/src/tclxstr.c
@@ -91,7 +91,7 @@ Tcl_ClengthCmd (clientData, interp, argc, argv)
         return TCL_ERROR;
     }
 
-    sprintf (interp->result, "%d", strlen (argv[1]));
+    sprintf (interp->result, "%lu", strlen (argv[1]));
     return TCL_OK;
 
 } /* Tcl_ClengthCmd */
