diff --git a/ports/rp2/datetime_patch.c b/ports/rp2/datetime_patch.c
index 810af4cf1..73bea7429 100644
--- a/ports/rp2/datetime_patch.c
+++ b/ports/rp2/datetime_patch.c
@@ -38,5 +38,5 @@ struct tm *localtime_r(const time_t *__restrict time, struct tm *__restrict loca
 }
 
 time_t mktime(struct tm *__restrict tm) {
-    return timeutils_mktime(tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+    return timeutils_mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
 }