1 files changed, 1 insertions, 1 deletions

diff --git a/src/callproc.c b/src/callproc.c
index db602f538c9..2fb5b1d5194 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -1099,7 +1099,7 @@ add_env (char **env, char **new_env, char *string)
       char *p = *ep, *q = string;
       while (ok)
         {
-          if (*q != *p)
+          if (*p && *q != *p)
             break;
           if (*q == 0)
             /* The string is a lone variable name; keep it for now, we