--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -194,17 +194,20 @@ var UninstallObserver = {
 
       // Clear any IndexedDB storage created by the extension
       let baseURI = NetUtil.newURI(`moz-extension://${uuid}/`);
       let principal = Services.scriptSecurityManager.createCodebasePrincipal(
         baseURI, {});
       Services.qms.clearStoragesForPrincipal(principal);
 
       // Clear localStorage created by the extension
-      Services.domStorageManager.getStorage(null, principal).clear();
+      let storage = Services.domStorageManager.getStorage(null, principal);
+      if (storage) {
+        storage.clear();
+      }
     }
 
     if (!this.leaveUuid) {
       // Clear the entry in the UUID map
       UUIDMap.remove(addon.id);
     }
   },
 };