diff --git a/dlls/shell32/appbar.c b/dlls/shell32/appbar.c
index 212ee37..6bd60da 100644
--- a/dlls/shell32/appbar.c
+++ b/dlls/shell32/appbar.c
@@ -74,9 +74,20 @@ UINT_PTR WINAPI SHAppBarMessage(DWORD msg, PAPPBARDATA data)

     UINT_PTR ret = 0;

-    TRACE("msg=%d, data={cb=%d, hwnd=%p, callback=%x, edge=%d, rc=%s, lparam=%lx}\n",
-            msg, data->cbSize, data->hWnd, data->uCallbackMessage, data->uEdge,
-            wine_dbgstr_rect(&data->rc), data->lParam);
+    TRACE("msg=%d, data={cb=%d, hwnd=%p}\n", msg, data->cbSize, data->hWnd);
+
+    /* These members are message dependent, only trace them if initialized */
+    if (data->uCallbackMessage)
+        TRACE("callback: %x\n", data->uCallbackMessage);
+
+    if (data->uEdge)
+        TRACE("edge: %d\n", data->uEdge);
+
+    if (&data->rc)
+        TRACE("rc: %s\n", wine_dbgstr_rect(&data->rc));
+
+    if (data->lParam)
+        TRACE("lParam: %lx\n", data->lParam);

     if (data->cbSize < sizeof(APPBARDATA))
     {