diff --git a/lib/des/dh.c b/lib/des/dh.c
index 9ee8eee6d..f4dff12c7 100644
--- a/lib/des/dh.c
+++ b/lib/des/dh.c
@@ -207,7 +207,7 @@ DH_compute_key(unsigned char *shared_key,
     int codes;
 
     if (!DH_check_pubkey(dh, peer_pub_key, &codes) || codes != 0)
-	return 0;
+	return -1;
 
     return dh->meth->compute_key(shared_key, peer_pub_key, dh);
 }