diff --git a/daemon/gdm-session.c b/daemon/gdm-session.c
index f759d2d..d154716 100644
--- a/daemon/gdm-session.c
+++ b/daemon/gdm-session.c
@@ -373,9 +373,12 @@ get_system_session_dirs (void)
 #ifdef ENABLE_WAYLAND_SUPPORT
                 DATADIR "/wayland-sessions/",
 #endif
+                NULL,
                 NULL
         };
 
+        search_dirs[4] = getenv("GDM_SESSIONS_DIR") != NULL ? getenv("GDM_SESSIONS_DIR") : NULL;
+
         return search_dirs;
 }