diff --git a/src/mail.c b/src/mail.c
index 82c7c0925..946f81634 100644
--- a/src/mail.c
+++ b/src/mail.c
@@ -91,7 +91,7 @@ void
 getmailstatus()
 {
     char *emailbox;
-    if (emailbox = nh_getenv("MAIL")) {
+    if ((emailbox = nh_getenv("MAIL")) != 0) {
         mailbox = (char *) alloc((unsigned) strlen(emailbox));
         Strcpy(mailbox, emailbox);
     }