diff --git a/src/octoprint/static/js/app/dataupdater.js b/src/octoprint/static/js/app/dataupdater.js
index 4172b459..73a4a6d2 100644
--- a/src/octoprint/static/js/app/dataupdater.js
+++ b/src/octoprint/static/js/app/dataupdater.js
@@ -33,8 +33,7 @@ function DataUpdater(allViewModels) {
     };
 
     self._onclose = function(e) {
-        if (e.code == 1000) {
-            // it was us calling close
+        if (e.code == SOCKJS_CLOSE_NORMAL) {
             return;
         }
         if (self._autoReconnectTrial >= self._autoReconnectDialogIndex) {
diff --git a/src/octoprint/templates/initscript.jinja2 b/src/octoprint/templates/initscript.jinja2
index 2351db39..4d8094a8 100644
--- a/src/octoprint/templates/initscript.jinja2
+++ b/src/octoprint/templates/initscript.jinja2
@@ -20,6 +20,8 @@
 
     var SOCKJS_URI = "{{ url_for('index') }}" + "sockjs";
     var SOCKJS_DEBUG = CONFIG_DEBUG;
+    // sockjs should define CLOSE_NORMAL for us, but they don't (from ws spec)
+    var SOCKJS_CLOSE_NORMAL = 1000
 
     var UI_API_KEY = "{{ uiApiKey }}";
     var VERSION = "{{ version }}";