diff --git a/src/sbbs3/zmodem.c b/src/sbbs3/zmodem.c
index 3e518809f26f37457bd01015e71bc6bf411e2103..44085c359b42c6bc7360bef6ed9e67734209cabd 100644
--- a/src/sbbs3/zmodem.c
+++ b/src/sbbs3/zmodem.c
@@ -1443,7 +1443,7 @@ BOOL zmodem_send_file(zmodem_t* zm, char* fname, FILE* fp, BOOL request_init, ti
 	p += strlen(p) + 1;
 
 	sprintf(p,"%lu %lo %lo %d %u %lu %d"
-		,s.st_size
+		,(ulong)s.st_size
 		,s.st_mtime
 		,0						/* file mode */
 		,0						/* serial number */