diff --git a/src/core.h b/src/core.h
index 524dd62..d39eda4 100644
--- a/src/core.h
+++ b/src/core.h
@@ -14,7 +14,7 @@ extern int max_clients;
 extern int num_clients;
 extern bool redirect;
 /* max_client logic only applies for files larger than 1024 bytes. */
-#define FILE_SIZE_THRESHOLD 1024
+#define FILE_SIZE_THRESHOLD 1024ULL
 
 enum tip_client_state {
 	TIP_CLIENT_PENDING		= 0,