diff --git a/static/js/compose.js b/static/js/compose.js
index 5c8981f3b2..216630ab2b 100644
--- a/static/js/compose.js
+++ b/static/js/compose.js
@@ -741,11 +741,7 @@ exports.initialize = function () {
 
     resize.watch_manual_resize("#compose-textarea");
 
-    // Run a feature test and decide whether to display
-    // the "Attach files" button
-    if (window.XMLHttpRequest && (new XMLHttpRequest()).upload) {
-        $("#compose #attach_files").removeClass("notdisplayed");
-    }
+    upload.feature_check($("#compose #attach_files"));
 
     // Lazy load the Dropbox script, since it can slow our page load
     // otherwise, and isn't enabled for all users. Also, this Dropbox
diff --git a/static/js/upload.js b/static/js/upload.js
index 3fdd074577..03f9cd9803 100644
--- a/static/js/upload.js
+++ b/static/js/upload.js
@@ -21,6 +21,13 @@ function clear_out_file_list(jq_file_list) {
     //    $("#file_input").val("");
 }
 
+// Show the upload button only if the browser supports it.
+exports.feature_check = function (upload_button) {
+    if (window.XMLHttpRequest && (new XMLHttpRequest()).upload) {
+        upload_button.removeClass("notdisplayed");
+    }
+};
+
 exports.options = function (config) {
     var textarea;
     var send_button;