diff --git a/lib/des/dh.c b/lib/des/dh.c
index c12c2731c..017713dd7 100644
--- a/lib/des/dh.c
+++ b/lib/des/dh.c
@@ -201,7 +201,7 @@ DH_compute_key(unsigned char *shared_key,
 {
     int codes;
 
-    if (!DH_check_pubkey(dh, peer_pub_key, &codes))
+    if (!DH_check_pubkey(dh, peer_pub_key, &codes) || codes != 0)
 	return 0;
 
     return dh->meth->compute_key(shared_key, peer_pub_key, dh);