--- a/dom/media/DecoderDoctorDiagnostics.cpp
+++ b/dom/media/DecoderDoctorDiagnostics.cpp
@@ -706,17 +706,17 @@ DecoderDoctorDiagnostics::StoreMediaKeyS
     return;
   }
 
   RefPtr<DecoderDoctorDocumentWatcher> watcher =
     DecoderDoctorDocumentWatcher::RetrieveOrCreate(aDocument);
 
   if (NS_WARN_IF(!watcher)) {
     DD_WARN("DecoderDoctorDiagnostics[%p]::StoreMediaKeySystemAccess(nsIDocument* aDocument=%p, keysystem='%s', supported=%d, call site '%s') - Could not create document watcher",
-            this, NS_ConvertUTF16toUTF8(aKeySystem).get(), aIsSupported, aCallSite);
+            this, aDocument, NS_ConvertUTF16toUTF8(aKeySystem).get(), aIsSupported, aCallSite);
     return;
   }
 
   mKeySystem = aKeySystem;
   mIsKeySystemSupported = aIsSupported;
 
   // StoreDiagnostics should only be called once, after all data is available,
   // so it is safe to Move() from this object.