diff --git a/app/assets/javascripts/discourse/lib/utilities.js b/app/assets/javascripts/discourse/lib/utilities.js
index 5799ee130b5..20ed59f0a41 100644
--- a/app/assets/javascripts/discourse/lib/utilities.js
+++ b/app/assets/javascripts/discourse/lib/utilities.js
@@ -279,7 +279,7 @@ Discourse.Utilities = {
   **/
   allowsAttachments: function() {
     return Discourse.Utilities.authorizesAllExtensions() ||
-           (/(png|jpg|jpeg|gif|bmp|tif|tiff)/i).test(Discourse.SiteSettings.authorized_extensions);
+           !(/((png|jpg|jpeg|gif|bmp|tif|tiff)(,\s)?)+$/i).test(Discourse.Utilities.authorizedExtensions());
   },
 
   displayErrorForUpload: function(data) {
diff --git a/app/assets/javascripts/discourse/templates/modal/upload_selector.js.handlebars b/app/assets/javascripts/discourse/templates/modal/upload_selector.js.handlebars
index df8e01d87d7..eca424b1cf3 100644
--- a/app/assets/javascripts/discourse/templates/modal/upload_selector.js.handlebars
+++ b/app/assets/javascripts/discourse/templates/modal/upload_selector.js.handlebars
@@ -38,7 +38,7 @@
 
 <div class="modal-footer">
   <button class="btn btn-primary" {{action upload target="view"}}>
-    <span class='add-upload'><i {{bind-attr class="view.uploadIcon"}}></i><i class='fa fa-plus'></i></span>
+    <span class='add-upload'><i {{bind-attr class=":fa view.uploadIcon"}}></i><i class='fa fa-plus'></i></span>
     {{i18n upload}}
   </button>
   <a {{action closeModal}}>{{i18n cancel}}</a>
diff --git a/app/assets/javascripts/discourse/views/composer/composer_view.js b/app/assets/javascripts/discourse/views/composer/composer_view.js
index 1277464ce09..57957c32f0c 100644
--- a/app/assets/javascripts/discourse/views/composer/composer_view.js
+++ b/app/assets/javascripts/discourse/views/composer/composer_view.js
@@ -202,6 +202,13 @@ Discourse.ComposerView = Discourse.View.extend(Ember.Evented, {
       }
     });
 
+    // HACK to change the upload icon of the composer's toolbar
+    Em.run.scheduleOnce("afterRender", function() {
+      if (!Discourse.Utilities.allowsAttachments()) {
+        $("#wmd-image-button").addClass("image-only");
+      }
+    });
+
     this.editor.hooks.insertImageDialog = function(callback) {
       callback(null);
       self.get('controller').send('showUploadSelector', self);
diff --git a/app/assets/javascripts/discourse/views/modal/upload_selector_view.js b/app/assets/javascripts/discourse/views/modal/upload_selector_view.js
index 223dc3d467b..f6736bd34b9 100644
--- a/app/assets/javascripts/discourse/views/modal/upload_selector_view.js
+++ b/app/assets/javascripts/discourse/views/modal/upload_selector_view.js
@@ -18,7 +18,7 @@ Discourse.UploadSelectorView = Discourse.ModalBodyView.extend({
   classNames: ['upload-selector'],
 
   title: function() { return uploadTranslate("title"); }.property(),
-  uploadIcon: function() { return Discourse.Utilities.allowsAttachments() ? "fa-file-o" : "fa-picture-o"; }.property(),
+  uploadIcon: function() { return Discourse.Utilities.allowsAttachments() ? "fa-upload" : "fa-picture-o"; }.property(),
 
   tip: function() {
     var source = this.get("controller.local") ? "local" : "remote";
diff --git a/app/assets/stylesheets/common/base/pagedown.scss b/app/assets/stylesheets/common/base/pagedown.scss
index 3d7ec7c0f01..f73ebd46506 100644
--- a/app/assets/stylesheets/common/base/pagedown.scss
+++ b/app/assets/stylesheets/common/base/pagedown.scss
@@ -92,6 +92,10 @@
   content: "\f093";
 }
 
+#wmd-image-button.image-only:before {
+  content: "\f03e";
+}
+
 #wmd-olist-button:before {
   content: "\f0cb";
 }
diff --git a/test/javascripts/lib/utilities_test.js b/test/javascripts/lib/utilities_test.js
index bb3af6b23e2..9fbe4d22ca6 100644
--- a/test/javascripts/lib/utilities_test.js
+++ b/test/javascripts/lib/utilities_test.js
@@ -10,15 +10,15 @@ test("emailValid", function() {
 var validUpload = utils.validateUploadedFiles;
 
 test("validateUploadedFiles", function() {
-  ok(!validUpload(null), "no files are invalid");
-  ok(!validUpload(undefined), "undefined files are invalid");
-  ok(!validUpload([]), "empty array of files is invalid");
+  not(validUpload(null), "no files are invalid");
+  not(validUpload(undefined), "undefined files are invalid");
+  not(validUpload([]), "empty array of files is invalid");
 });
 
 test("uploading one file", function() {
   this.stub(bootbox, "alert");
 
-  ok(!validUpload([1, 2]));
+  not(validUpload([1, 2]));
   ok(bootbox.alert.calledWith(I18n.t('post.errors.too_many_uploads')));
 });
 
@@ -26,7 +26,7 @@ test("new user cannot upload images", function() {
   Discourse.SiteSettings.newuser_max_images = 0;
   this.stub(bootbox, "alert");
 
-  ok(!validUpload([{name: "image.png"}]), 'the upload is not valid');
+  not(validUpload([{name: "image.png"}]), 'the upload is not valid');
   ok(bootbox.alert.calledWith(I18n.t('post.errors.image_upload_not_allowed_for_new_user')), 'the alert is called');
 });
 
@@ -34,7 +34,7 @@ test("new user cannot upload attachments", function() {
   Discourse.SiteSettings.newuser_max_attachments = 0;
   this.stub(bootbox, "alert");
 
-  ok(!validUpload([{name: "roman.txt"}]));
+  not(validUpload([{name: "roman.txt"}]));
   ok(bootbox.alert.calledWith(I18n.t('post.errors.attachment_upload_not_allowed_for_new_user')));
 });
 
@@ -43,7 +43,7 @@ test("ensures an authorized upload", function() {
   var extensions = Discourse.SiteSettings.authorized_extensions.replace(/\|/g, ", ");
   this.stub(bootbox, "alert");
 
-  ok(!validUpload([html]));
+  not(validUpload([html]));
   ok(bootbox.alert.calledWith(I18n.t('post.errors.upload_not_authorized', { authorized_extensions: extensions })));
 });
 
@@ -53,7 +53,7 @@ test("prevents files that are too big from being uploaded", function() {
   Discourse.User.currentProp("trust_level", 1);
   this.stub(bootbox, "alert");
 
-  ok(!validUpload([image]));
+  not(validUpload([image]));
   ok(bootbox.alert.calledWith(I18n.t('post.errors.image_too_large', { max_size_kb: 5 })));
 });
 
@@ -80,7 +80,7 @@ test("allows valid uploads to go through", function() {
   var pastedImage = dummyBlob();
   ok(validUpload([pastedImage]));
 
-  ok(!bootbox.alert.calledOnce);
+  not(bootbox.alert.calledOnce);
 });
 
 var getUploadMarkdown = function(filename) {
@@ -104,15 +104,15 @@ test("isAnImage", function() {
     ok(utils.isAnImage(image), image + " is recognized as an image");
     ok(utils.isAnImage("http://foo.bar/path/to/" + image), image + " is recognized as an image");
   });
-  ok(!utils.isAnImage("file.txt"));
-  ok(!utils.isAnImage("http://foo.bar/path/to/file.txt"));
-  ok(!utils.isAnImage(""));
+  not(utils.isAnImage("file.txt"));
+  not(utils.isAnImage("http://foo.bar/path/to/file.txt"));
+  not(utils.isAnImage(""));
 });
 
 test("avatarUrl", function() {
-  blank(Discourse.Utilities.avatarUrl('', 'tiny'), "no template returns blank");
-  equal(Discourse.Utilities.avatarUrl('/fake/template/{size}.png', 'tiny'), "/fake/template/" + 20*window.devicePixelRatio + ".png", "simple avatar url");
-  equal(Discourse.Utilities.avatarUrl('/fake/template/{size}.png', 'large'), "/fake/template/" + 45*window.devicePixelRatio +  ".png", "different size");
+  blank(utils.avatarUrl('', 'tiny'), "no template returns blank");
+  equal(utils.avatarUrl('/fake/template/{size}.png', 'tiny'), "/fake/template/" + 20*window.devicePixelRatio + ".png", "simple avatar url");
+  equal(utils.avatarUrl('/fake/template/{size}.png', 'large'), "/fake/template/" + 45*window.devicePixelRatio +  ".png", "different size");
 });
 
 test("avatarImg", function() {
@@ -120,27 +120,38 @@ test("avatarImg", function() {
   window.devicePixelRatio = 2;
 
   var avatarTemplate = "/path/to/avatar/{size}.png";
-  equal(Discourse.Utilities.avatarImg({avatarTemplate: avatarTemplate, size: 'tiny'}),
+  equal(utils.avatarImg({avatarTemplate: avatarTemplate, size: 'tiny'}),
         "<img width='20' height='20' src='/path/to/avatar/40.png' class='avatar'>",
         "it returns the avatar html");
 
-  equal(Discourse.Utilities.avatarImg({avatarTemplate: avatarTemplate, size: 'tiny', title: 'evilest trout'}),
+  equal(utils.avatarImg({avatarTemplate: avatarTemplate, size: 'tiny', title: 'evilest trout'}),
         "<img width='20' height='20' src='/path/to/avatar/40.png' class='avatar' title='evilest trout'>",
         "it adds a title if supplied");
 
-  equal(Discourse.Utilities.avatarImg({avatarTemplate: avatarTemplate, size: 'tiny', extraClasses: 'evil fish'}),
+  equal(utils.avatarImg({avatarTemplate: avatarTemplate, size: 'tiny', extraClasses: 'evil fish'}),
         "<img width='20' height='20' src='/path/to/avatar/40.png' class='avatar evil fish'>",
         "it adds extra classes if supplied");
 
-  blank(Discourse.Utilities.avatarImg({avatarTemplate: "", size: 'tiny'}),
+  blank(utils.avatarImg({avatarTemplate: "", size: 'tiny'}),
         "it doesn't render avatars for invalid avatar template");
 
   window.devicePixelRatio = oldRatio;
 });
 
+test("allowsAttachments", function() {
+  Discourse.SiteSettings.authorized_extensions = "jpg|jpeg|gif";
+  not(utils.allowsAttachments(), "no attachments allowed by default");
+
+  Discourse.SiteSettings.authorized_extensions = "jpg|jpeg|gif|*";
+  ok(utils.allowsAttachments(), "attachments are allowed when all extensions are allowed");
+
+  Discourse.SiteSettings.authorized_extensions = "jpg|jpeg|gif|pdf";
+  ok(utils.allowsAttachments(), "attachments are allowed when at least one extension is not an image extension");
+});
+
 test("defaultHomepage", function() {
   Discourse.SiteSettings.top_menu = "latest|top|hot";
-  equal(Discourse.Utilities.defaultHomepage(), "latest", "default homepage is the first item in the top_menu site setting");
+  equal(utils.defaultHomepage(), "latest", "default homepage is the first item in the top_menu site setting");
 });
 
 module("Discourse.Utilities.cropAvatar with animated avatars", {
@@ -150,7 +161,7 @@ module("Discourse.Utilities.cropAvatar with animated avatars", {
 asyncTestDiscourse("cropAvatar", function() {
   expect(1);
 
-  Discourse.Utilities.cropAvatar("/path/to/avatar.gif", "image/gif").then(function(avatarTemplate) {
+  utils.cropAvatar("/path/to/avatar.gif", "image/gif").then(function(avatarTemplate) {
     equal(avatarTemplate, "/path/to/avatar.gif", "returns the url to the gif when animated gif are enabled");
     start();
   });