diff --git a/rtapd.c b/rtapd.c
index 4da7384..31c84e1 100644
--- a/rtapd.c
+++ b/rtapd.c
@@ -347,7 +347,7 @@ int send_tnpp_packet(int fd, struct sockaddr_un *sun, unsigned char *data,
   int length, crc;
 
   if (len > (MAX_PACKET_SIZE - 14))
-    return;
+    return 0;
   serial++;
   if (serial > 255)
     serial = 1;
diff --git a/vsnppd.c b/vsnppd.c
index e0f83e2..4089e28 100644
--- a/vsnppd.c
+++ b/vsnppd.c
@@ -64,7 +64,7 @@ int send_tnpp_packet(int fd, struct sockaddr_un *sun, unsigned char *data,
   int length, crc;
 
   if (len > (MAX_PACKET_SIZE - 14))
-    return;
+    return 0;
   snprintf(buf, sizeof(buf) - 1, "%c%04X%02X%04X%02X%c", '\01', tnpp_to, 20,
 	   tnpp_from, 0, '\02');
   length = strlen(buf);