diff --git a/unpacked/jax/output/CommonHTML/autoload/mmultiscripts.js b/unpacked/jax/output/CommonHTML/autoload/mmultiscripts.js
index f19a15e5d..1a1914e17 100644
--- a/unpacked/jax/output/CommonHTML/autoload/mmultiscripts.js
+++ b/unpacked/jax/output/CommonHTML/autoload/mmultiscripts.js
@@ -45,7 +45,7 @@ MathJax.Hub.Register.StartupHook("CommonHTML Jax Ready",function () {
       //
       var base, bbox;
       if (stretch) {
-        base = node.getElementsByTagName("mjx-base")[0];
+        base = CHTML.getNode(node,"mjx-base");
       } else {
         this.CHTMLaddChild(node,0,{type:"mjx-base", noBBox:true, forceChild:true});
         base = node.firstChild;
@@ -137,10 +137,10 @@ MathJax.Hub.Register.StartupHook("CommonHTML Jax Ready",function () {
     //
     CHTMLgetScripts: function (BOX,BBOX,stretch,node) {
       if (stretch) {
-        BOX.sub = node.getElementsByTagName("mjx-sub")[0];
-        BOX.sup = node.getElementsByTagName("mjx-sup")[0];
-        BOX.presub = node.getElementsByTagName("mjx-presub")[0];
-        BOX.presup = node.getElementsByTagName("mjx-presup")[0];
+        BOX.sub = CHTML.getNode(node,"mjx-sub");
+        BOX.sup = CHTML.getNode(node,"mjx-sup");
+        BOX.presub = CHTML.getNode(node,"mjx-presub");
+        BOX.presup = CHTML.getNode(node,"mjx-presup");
         BBOX.sub = this.CHTMLbbox.sub;
         BBOX.sup = this.CHTMLbbox.sup;
         BBOX.presub = this.CHTMLbbox.presub;
diff --git a/unpacked/jax/output/CommonHTML/autoload/multiline.js b/unpacked/jax/output/CommonHTML/autoload/multiline.js
index 3b30c07f4..fcccc549a 100644
--- a/unpacked/jax/output/CommonHTML/autoload/multiline.js
+++ b/unpacked/jax/output/CommonHTML/autoload/multiline.js
@@ -505,9 +505,9 @@ MathJax.Hub.Register.StartupHook("CommonHTML Jax Ready",function () {
       //
       if (end.length === 0) {
         var NODE = this.CHTMLnodeElement(),
-            stack = NODE.getElementsByTagName("mjx-stack")[0],
-            sup = NODE.getElementsByTagName("mjx-sup")[0],
-            sub = NODE.getElementsByTagName("mjx-sub")[0];
+            stack = CHTML.getNode(NODE,"mjx-stack"),
+            sup = CHTML.getNode(NODE,"mjx-sup"),
+            sub = CHTML.getNode(NODE,"mjx-sub");
         if (stack)      node.appendChild(stack);
           else if (sup) node.appendChild(sup);
           else if (sub) node.appendChild(sub);
@@ -569,9 +569,9 @@ MathJax.Hub.Register.StartupHook("CommonHTML Jax Ready",function () {
       //
       if (start.length < 1) {
         NODE = this.CHTMLnodeElement();
-        var prestack = NODE.getElementsByTagName("mjx-prestack")[0],
-            presup = NODE.getElementsByTagName("mjx-presup")[0],
-            presub = NODE.getElementsByTagName("mjx-presub")[0];
+        var prestack = CHTML.getNode(NODE,"mjx-prestack"),
+            presup = CHTML.getNode(NODE,"mjx-presup"),
+            presub = CHTML.getNode(NODE,"mjx-presub");
         if (prestack)      node.appendChild(prestack);
           else if (presup) node.appendChild(presup);
           else if (presub) node.appendChild(presub);
@@ -598,9 +598,9 @@ MathJax.Hub.Register.StartupHook("CommonHTML Jax Ready",function () {
       //
       if (end.length === 0) {
         NODE = this.CHTMLnodeElement();
-        var stack = NODE.getElementsByTagName("mjx-stack")[0],
-            sup = NODE.getElementsByTagName("mjx-sup")[0],
-            sub = NODE.getElementsByTagName("mjx-sub")[0];
+        var stack = CHTML.getNode(NODE,"mjx-stack"),
+            sup = CHTML.getNode(NODE,"mjx-sup"),
+            sub = CHTML.getNode(NODE,"mjx-sub");
         if (stack)      node.appendChild(stack);
           else if (sup) node.appendChild(sup);
           else if (sub) node.appendChild(sub);
diff --git a/unpacked/jax/output/CommonHTML/jax.js b/unpacked/jax/output/CommonHTML/jax.js
index 54863d260..b51900f06 100644
--- a/unpacked/jax/output/CommonHTML/jax.js
+++ b/unpacked/jax/output/CommonHTML/jax.js
@@ -335,6 +335,22 @@
     ucMatch: HTML.ucMatch,
     setScript: HTML.setScript,
     
+    //
+    //  This replaces node.getElementsByTagName(type)[0]
+    //  and should be replaced by that if we go back to using
+    //  custom tags
+    //
+    getNode: (document.getElementsByClassName ? 
+      function (node,type) {return node.getElementsByClassName(type)[0]} :
+      function (node,type) {
+        var nodes = node.getElementsByTagName("span");
+        var name = RegExp("\\b"+type+"\\b");
+        for (var i = 0, m = nodes.length; i < m; i++) {
+          if (name.test(nodes[i].className)) return nodes[i];
+        }
+      }
+    ),
+    
 
     /********************************************/
     
@@ -361,7 +377,7 @@
         //  Remove any existing output
         //
         prev = script.previousSibling;
-	if (prev && prev.className.substr(0,9) === "mjx-chtml")
+	if (prev && prev.className && String(prev.className).substr(0,9) === "mjx-chtml")
 	  prev.parentNode.removeChild(prev);
         //
         //  Add the node for the math and mark it as being processed
@@ -1328,7 +1344,7 @@
         if (child) {
           var type = options.childNodes;
           if (type) {
-            if (type instanceof Array) type = type[i];
+            if (type instanceof Array) type = type[i]||"span";
             node = CHTML.addElement(node,type);
           }
           cnode = child.toCommonHTML(node,options.childOptions);
@@ -2035,9 +2051,9 @@
         //
         var base, under, over, nodes = [];
         if (stretch) {
-          base = node.getElementsByTagName("mjx-op")[0];
-          under = node.getElementsByTagName("mjx-under")[0];
-          over = node.getElementsByTagName("mjx-over")[0];
+          base = CHTML.getNode(node,"mjx-op");
+          under = CHTML.getNode(node,"mjx-under");
+          over = CHTML.getNode(node,"mjx-over");
           nodes[0] = base; nodes[1] = under||over; nodes[2] = over;
         } else {
           var types = ["mjx-op","mjx-under","mjx-over"];
@@ -2235,9 +2251,9 @@
         //
         var base, sub, sup;
         if (stretch) {
-          base = node.getElementsByTagName("mjx-base")[0];
-          sub = node.getElementsByTagName("mjx-sub")[0];
-          sup = node.getElementsByTagName("mjx-sup")[0];
+          base = CHTML.getNode(node,"mjx-base");
+          sub = CHTML.getNode(node,"mjx-sub");
+          sup = CHTML.getNode(node,"mjx-sup");
         } else {
           var types = ["mjx-base","mjx-sub","mjx-sup"];
           if (this.sup === 1) types[1] = types[2];