diff --git a/content/options.js b/content/options.js
index fc2d794..96d8a5b 100644
--- a/content/options.js
+++ b/content/options.js
@@ -17,7 +17,7 @@ window.addEventListener("load", function (event) {
   }, false);
 }, false);
 
-function pick_file(pref, title) {
+function pick_file(textboxId, title) {
   var nsIFilePicker = Components.interfaces.nsIFilePicker;
   var fp = Components.classes["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);
   fp.init(window, "Select the "+title+" binary", nsIFilePicker.modeOpen);
@@ -26,7 +26,7 @@ function pick_file(pref, title) {
     if( rv != nsIFilePicker.returnOK) {
       return;
     }
-    pref.value = fp.file.path;
+    document.getElementById(textboxId).value = fp.file.path;
   });
 }
 
diff --git a/content/options.xhtml b/content/options.xhtml
index ab43acf..fc34134 100644
--- a/content/options.xhtml
+++ b/content/options.xhtml
@@ -15,12 +15,12 @@
     <hbox align="baseline">
       <label control="latex_textbox" value="Path to latex executable:" />
       <html:input preference="tblatex.latex_path" id="latex_textbox" />
-      <button label="Browse..." oncommand="pick_file(document.getElementsByTagName('html:input')[0], 'latex');" />
+      <button label="Browse..." oncommand="pick_file('latex_textbox', 'latex');" />
     </hbox>
     <hbox align="baseline">
       <label control="dvipng_textbox" value="Path to dvipng executable:" />
       <html:input preference="tblatex.dvipng_path" id="dvipng_textbox" />
-      <button label="Browse..." oncommand="pick_file(document.getElementsByTagName('html:input')[1], 'dvipng');" />
+      <button label="Browse..." oncommand="pick_file('dvipng_textbox', 'dvipng');" />
     </hbox>
     <label style="text-decoration: underline; color: navy; cursor: pointer" value="Open the autodetection dialog"
       onclick="open_autodetect();" />