diff --git a/gtk/gtkentry.c b/gtk/gtkentry.c
index b95fd8b901..ebae2c0cbd 100644
--- a/gtk/gtkentry.c
+++ b/gtk/gtkentry.c
@@ -9987,6 +9987,12 @@ gtk_entry_set_completion (GtkEntry           *entry,
           old->priv->completion_timeout = 0;
         }
 
+      if (old->priv->check_completion_idle)
+        {
+          g_source_destroy (old->priv->check_completion_idle);
+          old->priv->check_completion_idle = NULL;
+        }
+
       if (gtk_widget_get_mapped (old->priv->popup_window))
         _gtk_entry_completion_popdown (old);