diff --git a/devtools/shared/deprecated-sync-thenables.js b/devtools/shared/deprecated-sync-thenables.js
index 4490e702d2e2..29736c0dac96 100644
--- a/devtools/shared/deprecated-sync-thenables.js
+++ b/devtools/shared/deprecated-sync-thenables.js
@@ -61,6 +61,9 @@ function defer() {
       }
 
       return deferred.promise;
+    },
+    catch: function (callback) {
+      return this.then(null, callback);
     }
   };