diff --git a/src/common/proto-irc.c b/src/common/proto-irc.c
index c0c75420..25dfc2a8 100644
--- a/src/common/proto-irc.c
+++ b/src/common/proto-irc.c
@@ -1358,6 +1358,7 @@ handle_message_tag_time (const char *time, message_tags_data *tags_data)
 			return;
 
 		t.tm_year -= 1900;
+		t.tm_mon -= 1;
 		t.tm_isdst = 0; /* day light saving time */
 
 		tags_data->timestamp = mktime (&t);