diff --git a/src/tclspice.c b/src/tclspice.c
index 367eb334e..7e8e47b92 100644
--- a/src/tclspice.c
+++ b/src/tclspice.c
@@ -2433,7 +2433,7 @@ tmeasure TCL_CMDPROCARGS(clientData, interp, argc, argv)
         return TCL_ERROR;
     }
 
-    wl = wl_build((char **)argv);
+    wl = wl_build((const char * const *)argv);
 
     get_measure2(wl, &mvalue, NULL, FALSE);