diff --git a/keys.c b/keys.c
index 74b57c4..61ffb91 100644
--- a/keys.c
+++ b/keys.c
@@ -107,6 +107,8 @@ determine_hash_delay(uint32_t key_id)
   double diff, min_diff;
   int i, nsecs;
 
+  memset(&pkt, 0, sizeof (pkt));
+
   for (i = 0; i < 10; i++) {
     LCL_ReadRawTime(&before);
     KEY_GenerateAuth(key_id, (unsigned char *)&pkt, NTP_NORMAL_PACKET_LENGTH,