diff --git a/src/log.c b/src/log.c
index 89318b82c..c8f85695b 100644
--- a/src/log.c
+++ b/src/log.c
@@ -3319,7 +3319,7 @@ struct ist *build_log_header(struct log_header hdr, size_t *nbelem)
 				break;
 			}
 			else if (metadata && metadata[LOG_META_TIME].len >= LOG_ISOTIME_MINLEN) {
-				int month;
+				uint month;
 				char *timestamp = metadata[LOG_META_TIME].ptr;
 
 				/* iso time always begins like this: '1970-01-01T00:00:00' */