diff --git a/lib/core/file.js b/lib/core/file.js
index 65e5e634..bc97ddaa 100644
--- a/lib/core/file.js
+++ b/lib/core/file.js
@@ -73,15 +73,25 @@ class File {
         });
       },
       function downloadTheFile(next) {
+        let alreadyCalledBack = false;
+        function doCallback(err) {
+          if (alreadyCalledBack) {
+            return;
+          }
+          alreadyCalledBack = true;
+          next(err);
+        }
         request(url)
           .on('response', function (response) {
             if (response.statusCode !== 200) {
-              next('Getting file returned code ' + response.statusCode);
+              doCallback('Getting file returned code ' + response.statusCode);
             }
           })
-          .on('error', next)
+          .on('error', doCallback)
           .pipe(fs.createWriteStream(filename))
-          .on('finish', next);
+          .on('finish', () => {
+            doCallback();
+          });
       },
       function readFile(next) {
         fs.readFile(filename, next);