diff --git a/browser/app/macbuild/Contents/Resources/scripting.sdef.in b/browser/app/macbuild/Contents/Resources/scripting.sdef.in
index 19b1c71ae..36717f51a 100644
--- a/browser/app/macbuild/Contents/Resources/scripting.sdef.in
+++ b/browser/app/macbuild/Contents/Resources/scripting.sdef.in
@@ -295,13 +295,13 @@
       <cocoa class="NSScriptCommand"/>
       <direct-parameter type="specifier" description="the object to reload"/>
     </command>
-    <command name="runJS" code="104FxrJS" description="Runs JavaScript in the context of an object.">
+    <command name="run" code="104FxrJS" description="Runs JavaScript in the context of an object.">
       <cocoa class="NSScriptCommand"/>
       <direct-parameter type="specifier" description="the object context"/>
-      <parameter name="script" code="scpt" type="text" description="The script source text.">
+      <parameter name="JavaScript" code="jscp" type="text" description="the JavaScript source text">
         <cocoa key="script"/>
       </parameter>
-      <result type="text" description="String value returned by the script."/>
+      <result type="text" description="string value returned by the script"/>
     </command>
     <class name="tab" code="BTab" description="A %MAC_APP_NAME% browser window tab." inherits="item" plural="tabs">
       <cocoa class="GeckoTab"/>
@@ -332,7 +332,7 @@
       <responds-to name="reload">
         <cocoa method="handleReloadScriptCommand:"/>
       </responds-to>
-      <responds-to name="runJS">
+      <responds-to name="run">
         <cocoa method="handleRunJavaScriptCommand:"/>
       </responds-to>
 <!--
diff --git a/browser/components/nsBrowserGlue.js b/browser/components/nsBrowserGlue.js
index b0edab4dd..2e73cd95c 100644
--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -980,10 +980,20 @@ BrowserGlue.prototype = {
           }
         },
         runScriptInTabAtIndexInWindow : function(index, window_index,
-            script) {
-          Services.console.logStringMessage("Got script: "+script);
-          throw Components.Exception("NYI", Cr.NS_ERROR_FAILURE);
-          return null;
+            script, rval) {
+          try {
+            let win = this.getWindow(window_index);
+            let tab = win.gBrowser.tabs[index].linkedBrowser;
+            let f = new Function("window", "document", ""+script);
+            let g = (t) => {
+              return f(t.contentWindow, t.contentDocument);
+            };
+            rval.value = g(tab);
+          } catch(e) {
+            Services.console.logStringMessage("AS-to-JS error: "+e);
+            return false;
+          }
+          return true;
         }
       }
 
diff --git a/toolkit/components/applescript/src/MacScripting.mm b/toolkit/components/applescript/src/MacScripting.mm
index acfe10dbd..61fca9e44 100644
--- a/toolkit/components/applescript/src/MacScripting.mm
+++ b/toolkit/components/applescript/src/MacScripting.mm
@@ -892,9 +892,10 @@ static BOOL didInit = NO;
       NSString *script = [args objectForKey:@"script"];
       if (script) {
         nsAutoCString s, r;
-        bool ok;
+        bool ok = false;
 
         s.Assign([script UTF8String]);
+        r.Truncate();
         if (NS_SUCCEEDED(applescriptService->RunScriptInTabAtIndexInWindow(mIndex,
                                                                            [mWindow orderedIndex],
                                                                            s, r, &ok))) {