diff --git a/dlls/ddraw/ddraw.c b/dlls/ddraw/ddraw.c
index 99c0a69abd0..25519d2a37c 100644
--- a/dlls/ddraw/ddraw.c
+++ b/dlls/ddraw/ddraw.c
@@ -5359,6 +5359,8 @@ static void CDECL device_parent_wined3d_device_created(struct wined3d_device_par
     TRACE("device_parent %p, device %p.\n", device_parent, device);
 }
 
+/* This is run from device_process_message() in wined3d, we can't take the
+ * wined3d mutex. */
 static void CDECL device_parent_mode_changed(struct wined3d_device_parent *device_parent)
 {
     struct IDirectDrawImpl *ddraw = ddraw_from_device_parent(device_parent);
diff --git a/dlls/wined3d/device.c b/dlls/wined3d/device.c
index d0768aa0aeb..17560c6ca45 100644
--- a/dlls/wined3d/device.c
+++ b/dlls/wined3d/device.c
@@ -5912,9 +5912,7 @@ LRESULT device_process_message(struct wined3d_device *device, HWND window, BOOL
     }
     else if (message == WM_DISPLAYCHANGE)
     {
-        wined3d_mutex_lock();
         device->device_parent->ops->mode_changed(device->device_parent);
-        wined3d_mutex_unlock();
     }
 
     if (unicode)