diff --git a/lib/Generate.js b/lib/Generate.js
index c2e799f2..bb47c4cf 100644
--- a/lib/Generate.js
+++ b/lib/Generate.js
@@ -23,10 +23,10 @@ function prepareCompiledJsFile(pipeFilename, dest) {
   const content = fs.readFileSync(dest, 'utf8');
   const finalContent = `
 ${before}
-var Elm = (function(module) {
+var Elm = (function() {
 ${patch(content)}
 return this.Elm;
-})({});
+}).call({});
 var pipeFilename = ${JSON.stringify(pipeFilename)};
 ${after}
   `.trim();
diff --git a/lib/Supervisor.js b/lib/Supervisor.js
index 43fcbd38..c8155757 100644
--- a/lib/Supervisor.js
+++ b/lib/Supervisor.js
@@ -272,6 +272,8 @@ function run(elmTestVersion, pipeFilename, report, processes, dest, watch) {
     // If just one process, run single-threaded.
     if (processes === 1) {
       var { run } = require(dest);
+      // Allow the generated file to be `require`d again (for watch mode).
+      delete require.cache[dest];
       var send = run(
         0,
         /** @type { (response: any) => void } */
diff --git a/templates/after.js b/templates/after.js
index 0689d426..05898f84 100644
--- a/templates/after.js
+++ b/templates/after.js
@@ -1,5 +1,7 @@
 function run(index, receive) {
   var app = Elm.Test.Generated.Main.init({ flags: index });
+  // Without this, each run leaks memory in single-threaded mode:
+  Elm = null;
   app.ports.elmTestPort__send.subscribe(receive);
   return app.ports.elmTestPort__receive.send;
 }