diff --git a/content/modal.html b/content/modal.html
index d1c1802..0195e7f 100644
--- a/content/modal.html
+++ b/content/modal.html
@@ -1,6 +1,7 @@
 <div id="diffModal" class="modal-dialog" tabindex="0" role="dialog" style="left: 274px; top: 180px; display: none;">
   <div class="modal-dialog-title modal-dialog-title-draggable">
     <span class="modal-dialog-title-text">Diff</span>
+    <span class="modal-dialog-title-text">(warning, only .gs and .html files will be synced)</span>
     <span class="github-diff-modal-close modal-dialog-title-close"></span>
   </div>
   <div class="modal-dialog-content">
@@ -133,4 +134,4 @@
     <button id="github-create-branch" type="button" class="goog-buttonset-default goog-buttonset-action" disabled="true">Create</button>
     <button type="button" class="github-branch-modal-close">Cancel</button>
   </div>
-</div>
\ No newline at end of file
+</div>
diff --git a/src/gas-api.js b/src/gas-api.js
index 3a279e7..d53c694 100644
--- a/src/gas-api.js
+++ b/src/gas-api.js
@@ -11,7 +11,7 @@ function pull(code) {
     }
     const name = match[1];
     const type = match[2];
-    
+
     if (!code.gas[file]) {
       return () => gasCreateFile(name, type)
       .then(() => {
@@ -20,7 +20,8 @@ function pull(code) {
     } else {
       return () => gasUpdateFile(name, code.github[file]);
     }
-  });
+  })
+  .filter(n => n != undefined);
 
   const delete_promises = changed.filter(f => !code.github[f])
   .map((file) => {
@@ -37,7 +38,7 @@ function pull(code) {
     showAlert("Nothing to do", LEVEL_WARN);
     return;
   }
-  
+
   getGasContext()
   .then(() => {
     return Promise.all(update_promises.map(f => f()))
@@ -206,4 +207,4 @@ function gasDeleteFile(file) {
       reject(new Error('Update file failed'));
     });
   });
-}
\ No newline at end of file
+}
diff --git a/src/gas-hub.js b/src/gas-hub.js
index 3d14579..661e255 100644
--- a/src/gas-hub.js
+++ b/src/gas-hub.js
@@ -7,7 +7,7 @@ const LEVEL_WARN = "info";
 const LEVEL_INFO = "promo";
 const observer = new MutationObserver((e) => {
   observer.disconnect();
-  $('.github-alert').remove();  
+  $('.github-alert').remove();
 });
 
 $(() => {
@@ -80,14 +80,14 @@ function initLoginContent() {
     $('#login').hover(() => {
       $('#login').addClass('goog-toolbar-menu-button-hover');
     }, () => {
-      $('#login').removeClass('goog-toolbar-menu-button-hover'); 
+      $('#login').removeClass('goog-toolbar-menu-button-hover');
     });
     $('#login').click(() => {
       if (chrome.runtime.openOptionsPage) {
         chrome.runtime.openOptionsPage();
       } else {
         window.open(chrome.runtime.getURL('options/options.html'));
-      }  
+      }
     });
     chrome.runtime.sendMessage({ cmd: "tab" });
   });
@@ -99,7 +99,7 @@ function initPageEvent() {
     ['repo', 'branch'].forEach((type) => {
       const container = $(`.${type}-menu`);
       const button = $(`#${type}Select`);
-      if (!container.is(event.target) 
+      if (!container.is(event.target)
         && !button.is(event.target)
         && container.has(event.target).length === 0
         && button.has(event.target).length == 0) {
@@ -203,8 +203,8 @@ function initPageEvent() {
         break;
       default:
         return;
-    } 
-    context[type] = content;    
+    }
+    context[type] = content;
     const bindName = `bind${type.capitalize()}`;
     Object.assign(context[bindName], { [context.id] : content });
     chrome.storage.sync.set({ [bindName]: context[bindName] }, () => {
@@ -265,6 +265,10 @@ function showDiff(code, type) {
     return gasFiles.indexOf(e) < 0;
   })
   .concat(gasFiles)
+  .filter((file) => {
+    const match = file.match(/(.*?)\.(gs|html)$/);
+    return match && match[1] && match[2];
+  })
   .reduce((diff, file) => {
     let mode = null;
     if (!oldCode[file]) {
@@ -279,7 +283,7 @@ function showDiff(code, type) {
     if (mode) {
       diffArr.splice(1, 0, mode);
     }
-    fileDiff = diffArr.join('\n');   
+    fileDiff = diffArr.join('\n');
     return diff + fileDiff;
   }, "");
 
@@ -331,7 +335,7 @@ function showDiff(code, type) {
 function updateRepo(repos) {
   $('.repo-menu').empty().append('<div class="github-new-repo github-item goog-menuitem"><div class="goog-menuitem-content">Create new repo</div></div>');
   $('.repo-menu').append('<div class="github-use-gist github-item goog-menuitem"><div class="goog-menuitem-content" github-content="repo" data="gist">Using Gist</div></div>');
-  
+
   repos.forEach((repo) => {
     let content = `<div class="github-item goog-menuitem"><div class="goog-menuitem-content" github-content="repo" data="${repo.fullName}">${repo.name}</div></div>`
     $('.repo-menu').append(content);
@@ -442,4 +446,4 @@ function showAlert(message, level=LEVEL_INFO) {
 
 String.prototype.capitalize = function() {
     return this.charAt(0).toUpperCase() + this.slice(1);
-}
\ No newline at end of file
+}