diff --git a/gio/gtask.c b/gio/gtask.c
index 346d2ec5b..f6c89c974 100644
--- a/gio/gtask.c
+++ b/gio/gtask.c
@@ -563,15 +563,22 @@ struct _GTask {
   /* This can’t be in the bit field because we access it from TRACE(). */
   gboolean thread_cancelled;
 
-  gboolean check_cancellable : 1;
-  gboolean completed : 1;
-  gboolean return_on_cancel : 1;
-  gboolean synchronous : 1;
+  /* Protected by the lock when task is threaded: */
   gboolean thread_complete : 1;
-  gboolean blocking_other_task : 1;
+  gboolean return_on_cancel : 1;
+  gboolean : 0;
+
+  /* Unprotected, but written to when task runs in thread: */
+  gboolean completed : 1;
   gboolean had_error : 1;
   gboolean result_set : 1;
   gboolean ever_returned : 1;
+  gboolean : 0;
+
+  /* Read-only once task runs in thread: */
+  gboolean check_cancellable : 1;
+  gboolean synchronous : 1;
+  gboolean blocking_other_task : 1;
 
   GError *error;
   union {