diff --git a/src/gswe-timestamp.c b/src/gswe-timestamp.c
index b4e6f83..3dee6e4 100644
--- a/src/gswe-timestamp.c
+++ b/src/gswe-timestamp.c
@@ -1025,13 +1025,13 @@ gswe_timestamp_set_gregorian_timezone(
         gdouble gregorian_timezone_offset,
         GError **err)
 {
+    gswe_timestamp_calculate_julian(timestamp, NULL);
     timestamp->priv->gregorian_timezone_offset = gregorian_timezone_offset;
+    timestamp->priv->valid_dates &= ~VALID_GREGORIAN;
 
     if (timestamp->priv->instant_recalc == TRUE) {
         gswe_timestamp_calculate_all(timestamp, err);
     }
-
-    gswe_timestamp_emit_changed(timestamp);
 }
 
 /**