diff --git a/scp.c b/scp.c
index 5db59b0a..78c7c14d 100644
--- a/scp.c
+++ b/scp.c
@@ -2873,8 +2873,8 @@ if (cptr == NULL) {
     }
 else
     cptr2 = NULL;
-if (cptr && sizeof (nbuf) > strlen (cptr) + strlen ("/simh.ini") + 1) {
-    sprintf(nbuf, "\"%s%s%ssimh.ini\"", cptr2 ? cptr2 : "", cptr, strchr (cptr, '/') ? "/" : "\\");
+if (cptr && (sizeof (nbuf) > strlen (cptr) + strlen ("/simh.ini") + 3)) {
+    snprintf(nbuf, sizeof (nbuf), "\"%s%s%ssimh.ini\"", cptr2 ? cptr2 : "", cptr, strchr (cptr, '/') ? "/" : "\\");
     stat = do_cmd (-1, nbuf) & ~SCPE_NOMESSAGE;         /* simh.ini proc cmd file */
     }
 if (SCPE_BARE_STATUS(stat) == SCPE_OPENERR)