diff --git a/lib/ConsoleAgent.js b/lib/ConsoleAgent.js
index f59a865..29c5da6 100644
--- a/lib/ConsoleAgent.js
+++ b/lib/ConsoleAgent.js
@@ -212,7 +212,7 @@ class ConsoleAgent extends Agent {
       };
     }
 
-    this[CHILD_PROCESS] = await this.createChildProcess([tempfile]);
+    this[CHILD_PROCESS] = await this.createChildProcess([...options.testHostArgs || [], tempfile]);
     this.hasFinishedCreatingChildProcess = true;
 
     if (this.isStopped && this[CHILD_PROCESS] === null) {
diff --git a/lib/agents/jsshell.js b/lib/agents/jsshell.js
index 8a3db75..a5d837d 100644
--- a/lib/agents/jsshell.js
+++ b/lib/agents/jsshell.js
@@ -11,13 +11,19 @@ const stackRe = /^([\s\S]*?)\r?\nStack:\r?\n([\s\S]*)$/;
 const stackFrameRe = /^(.*?)?@(.*?):(\d+):(\d+)?$/;
 
 class JSShell extends ConsoleAgent {
-  async evalScript(code, options = {}) {
-    if (options.module && this.args[0] !== '--module') {
-      this.args.unshift('--module');
+  constructor(options) {
+    super(options);
+    if (this.args.indexOf('--module') !== -1) {
+      throw new Error("Passing --module as a SpiderMonkey host argument is not supported.")
     }
+  }
 
-    if (!options.module && this.args[0] === '--module') {
-      this.args.shift();
+  async evalScript(code, options = {}) {
+    if (options.module) {
+      if (!options.testHostArgs) {
+        options.testHostArgs = [];
+      }
+      options.testHostArgs.push('--module');
     }
 
     return super.evalScript(code, options);