diff --git a/openbox/client.c b/openbox/client.c
index 27854756..1219f15d 100644
--- a/openbox/client.c
+++ b/openbox/client.c
@@ -2721,3 +2721,12 @@ ObClient *client_search_transient(ObClient *self, ObClient *search)
     }
     return NULL;
 }
+
+gchar* client_get_sm_client_id(ObClient *self)
+{
+    gchar *id = NULL;
+
+    if (!PROP_GETS(self->window, sm_client_id, locale, &id) && self->group)
+        PROP_GETS(self->group->leader, sm_client_id, locale, &id);
+    return id;
+}
diff --git a/openbox/client.h b/openbox/client.h
index fe37a7d7..610c8cd4 100644
--- a/openbox/client.h
+++ b/openbox/client.h
@@ -469,4 +469,6 @@ void client_set_layer(ObClient *self, int layer);
 
 guint client_monitor(ObClient *self);
 
+gchar* client_get_sm_client_id(ObClient *self);
+
 #endif