diff --git a/content/events/src/nsEventListenerManager.cpp b/content/events/src/nsEventListenerManager.cpp
index 6f27e4b1dd4..47b2d437364 100644
--- a/content/events/src/nsEventListenerManager.cpp
+++ b/content/events/src/nsEventListenerManager.cpp
@@ -754,20 +754,21 @@ nsEventListenerManager::AddScriptEventListener(nsISupports *aObject,
     }
   }
 
-  if (global) {
-    // This might be the first reference to this language in the global
-    // We must init the language before we attempt to fetch its context.
-    if (NS_FAILED(global->EnsureScriptEnvironment(aLanguage))) {
-      NS_WARNING("Failed to setup script environment for this language");
-      // but fall through and let the inevitable failure below handle it.
-    }
-
-    context = global->GetScriptContext(aLanguage);
+  if (!global) {
+    // This can happen; for example this document might have been
+    // loaded as data.
+    return NS_OK;
+  }
+  
+  // This might be the first reference to this language in the global
+  // We must init the language before we attempt to fetch its context.
+  if (NS_FAILED(global->EnsureScriptEnvironment(aLanguage))) {
+    NS_WARNING("Failed to setup script environment for this language");
+    // but fall through and let the inevitable failure below handle it.
   }
-  NS_ENSURE_TRUE(context, NS_ERROR_FAILURE);
 
-  NS_ASSERTION(global, "How could we possibly have a context without an "
-               "nsIScriptGlobalObject?");
+  context = global->GetScriptContext(aLanguage);
+  NS_ENSURE_TRUE(context, NS_ERROR_FAILURE);
 
   void *scope = global->GetScriptGlobal(aLanguage);
   nsresult rv;
diff --git a/content/events/test/Makefile.in b/content/events/test/Makefile.in
index e4a5a53c823..0e8d1a739c8 100644
--- a/content/events/test/Makefile.in
+++ b/content/events/test/Makefile.in
@@ -45,6 +45,7 @@ include $(DEPTH)/config/autoconf.mk
 include $(topsrcdir)/config/rules.mk
 
 _TEST_FILES = 	test_bug367781.html \
+		test_bug379120.html \
 		$(NULL)
 
 libs:: $(_TEST_FILES)
diff --git a/content/events/test/test_bug379120.html b/content/events/test/test_bug379120.html
new file mode 100644
index 00000000000..fac86ac5bad
--- /dev/null
+++ b/content/events/test/test_bug379120.html
@@ -0,0 +1,57 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=379120
+-->
+<head>
+  <title>Test for Bug 379120</title>
+  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>        
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=379120">Mozilla Bug 379120</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+/** Test for Bug 379120 **/
+
+    var originalString = "<test></test>";
+
+    // Parse the content into an XMLDocument
+    var parser = new DOMParser();
+    var originalDoc = parser.parseFromString(originalString, "text/xml");
+
+    var stylesheetText = 
+        "<xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' " +
+            "version='1.0' xmlns='http://www.w3.org/1999/xhtml'> " +
+
+          "<xsl:output method='xml' version='1.0' encoding='UTF-8' " +
+              "doctype-system='http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd' " +
+              "doctype-public='-//W3C//DTD XHTML 1.0 Transitional//EN' /> " +
+
+          "<xsl:template match='/'>" +
+            "<div onload='var i = 1'/>" + 
+            "<xsl:apply-templates />" +
+          "</xsl:template>" +
+        "</xsl:stylesheet>";
+    var stylesheet = parser.parseFromString(stylesheetText, "text/xml");
+
+    var processor = new XSLTProcessor();
+
+    var targetDocument;
+    processor.importStylesheet (stylesheet);
+    var transformedDocument = processor.transformToDocument (originalDoc);
+    is(transformedDocument.documentElement.getAttribute("onload"),
+       "var i = 1");
+    ok(transformedDocument.documentElement.onload === undefined,
+       "Shouldn't have onload handler");
+</script>
+</pre>
+</body>
+</html>
+
