diff --git a/panels/datetime/cc-timezone-map.c b/panels/datetime/cc-timezone-map.c
index 4d5075c88..3c7c8fcd8 100644
--- a/panels/datetime/cc-timezone-map.c
+++ b/panels/datetime/cc-timezone-map.c
@@ -426,8 +426,8 @@ set_location (CcTimezoneMap *map,
 
   info = tz_info_from_location (map->location);
 
-  map->selected_offset = tz_location_get_utc_offset (map->location)
-    / (60.0*60.0) + ((info->daylight) ? -1.0 : 0.0);
+  map->selected_offset = tz_location_get_base_utc_offset (map->location)
+    / (60.0*60.0);
   gtk_widget_queue_draw (GTK_WIDGET (map));
 
   g_signal_emit (map, signals[LOCATION_CHANGED], 0, map->location);
diff --git a/panels/datetime/tz.c b/panels/datetime/tz.c
index 5ef667690..4fe2305b0 100644
--- a/panels/datetime/tz.c
+++ b/panels/datetime/tz.c
@@ -181,14 +181,46 @@ tz_location_get_position (TzLocation *loc, double *longitude, double *latitude)
 	*latitude = loc->latitude;
 }
 
+/* For timezone map display purposes, we try to highlight regions of the
+ * world that keep the same time.  There is no reasonable API to discover
+ * this; at the moment we just group timezones by their non-daylight-savings
+ * UTC offset and hope that's good enough.  However, in some cases that
+ * produces confusing results.  For example, Irish Standard Time is legally
+ * defined as the country's summer time, with a negative DST offset in
+ * winter; but this results in the same observed clock times as countries
+ * that observe Western European (Summer) Time, not those that observe
+ * Central European (Summer) Time, so we should group Ireland with the
+ * former, matching the grouping implied by data/timezone_*.png.
+ *
+ * This is something of a hack, and there remain other problems with
+ * timezone grouping: for example, grouping timezones north and south of the
+ * equator together where DST is observed at different times of the year is
+ * dubious.
+ */
+struct {
+	const char *zone;
+	gint offset;
+} base_offset_overrides[] = {
+	{ "Europe/Dublin",  0 },
+};
+
 glong
-tz_location_get_utc_offset (TzLocation *loc)
+tz_location_get_base_utc_offset (TzLocation *loc)
 {
 	g_autoptr(TzInfo) tz_info = NULL;
 	glong offset;
+	guint i;
 
 	tz_info = tz_info_from_location (loc);
-	offset = tz_info->utc_offset;
+	offset = tz_info->utc_offset + (tz_info->daylight ? -3600 : 0);
+
+	for (i = 0; i < G_N_ELEMENTS (base_offset_overrides); i++) {
+		if (g_str_equal (loc->zone, base_offset_overrides[i].zone)) {
+			offset = base_offset_overrides[i].offset;
+			break;
+		}
+	}
+
 	return offset;
 }
 
diff --git a/panels/datetime/tz.h b/panels/datetime/tz.h
index b6b7ab9d0..feef16580 100644
--- a/panels/datetime/tz.h
+++ b/panels/datetime/tz.h
@@ -78,7 +78,7 @@ void       tz_location_get_position   (TzLocation *loc,
 char      *tz_location_get_country    (TzLocation *loc);
 gchar     *tz_location_get_zone       (TzLocation *loc);
 gchar     *tz_location_get_comment    (TzLocation *loc);
-glong      tz_location_get_utc_offset (TzLocation *loc);
+glong      tz_location_get_base_utc_offset (TzLocation *loc);
 gint       tz_location_set_locally    (TzLocation *loc);
 TzInfo    *tz_info_from_location      (TzLocation *loc);
 void       tz_info_free               (TzInfo *tz_info);