diff --git a/.eslintrc b/.eslintrc
index 356a6546..5a8de8df 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -32,6 +32,9 @@
             "nonwords": false,
         }],
         "strict": "error",
+        "wrap-iife": ["error", "outside", {
+            "functionPrototypeMethods": true,
+        }],
     },
     "ignorePatterns": [ "syntax-error.*" ],
     "overrides": [
diff --git a/index.js b/index.js
index 0e9bb5a2..4aa5f8e5 100644
--- a/index.js
+++ b/index.js
@@ -62,7 +62,7 @@ module.exports = (function () {
         if (!harness) harness = createExitHarness(opts, wait);
         return harness;
     }
-})();
+}());
 
 function createExitHarness(conf, wait) {
     var config = conf || {};
@@ -137,7 +137,7 @@ function createHarness(conf_) {
             st.on('result', function (r) {
                 if (!r.todo && !r.ok && typeof r !== 'string') test._exitCode = 1;
             });
-        })(t);
+        }(t));
 
         results.push(t);
         return t;
diff --git a/lib/test.js b/lib/test.js
index ed005cb6..bf27b818 100644
--- a/lib/test.js
+++ b/lib/test.js
@@ -92,7 +92,7 @@ function Test(name_, opts_, cb_) {
                 };
             }
             return val;
-        })(this, this[prop]);
+        }(this, this[prop]));
     }
 }