1 files changed, 1 insertions, 2 deletions

diff --git a/src/callproc.c b/src/callproc.c
index fae47b7a699..12621c90db5 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -1230,8 +1230,7 @@ child_setup (int in, int out, int err, register char **new_argv, int set_pgrp, L
 
     if (STRINGP (display))
       {
-        int vlen = strlen ("DISPLAY=") + strlen (SSDATA (display)) + 1;
-        char *vdata = (char *) alloca (vlen);
+        char *vdata = (char *) alloca (sizeof "DISPLAY=" + SBYTES (display));
         strcpy (vdata, "DISPLAY=");
         strcat (vdata, SSDATA (display));
         new_env = add_env (env, new_env, vdata);