diff --git a/toolkit/components/antitracking/StorageAccess.cpp b/toolkit/components/antitracking/StorageAccess.cpp
index d8061d097f45..eb80b0be8f61 100644
--- a/toolkit/components/antitracking/StorageAccess.cpp
+++ b/toolkit/components/antitracking/StorageAccess.cpp
@@ -235,7 +235,16 @@ StorageAccess StorageAllowedForWindow(nsPIDOMWindowInner* aWindow,
         *aRejectedReason);
   }
 
-  // No document? Let's return a generic rejected reason.
+  // No document? Try checking Private Browsing Mode without document
+  if (const nsCOMPtr<nsIGlobalObject> global = aWindow->AsGlobal()) {
+    if (const nsCOMPtr<nsIPrincipal> principal = global->PrincipalOrNull()) {
+      if (principal->GetPrivateBrowsingId() > 0) {
+        return StorageAccess::ePrivateBrowsing;
+      }
+    }
+  }
+
+  // Everything failed? Let's return a generic rejected reason.
   return StorageAccess::eDeny;
 }