--- a/devtools/client/jsonview/main.js
+++ b/devtools/client/jsonview/main.js
@@ -46,17 +46,15 @@ var JsonView = {
   // Message handlers for events from child processes
 
   /**
    * Save JSON to a file needs to be implemented here
    * in the parent process.
    */
   onSave: function (message) {
     JsonViewUtils.getTargetFile().then(file => {
-      if (file) {
-        JsonViewUtils.saveToFile(file, message.data);
-      }
-    });
+      JsonViewUtils.saveToFile(file, message.data);
+    }, () => {});
   }
 };
 
 // Exports from this module
 module.exports.JsonView = JsonView;

--- a/devtools/client/jsonview/utils.js
+++ b/devtools/client/jsonview/utils.js
@@ -14,35 +14,46 @@ const OPEN_FLAGS = {
   RDONLY: parseInt("0x01", 16),
   WRONLY: parseInt("0x02", 16),
   CREATE_FILE: parseInt("0x08", 16),
   APPEND: parseInt("0x10", 16),
   TRUNCATE: parseInt("0x20", 16),
   EXCL: parseInt("0x80", 16)
 };
 
+let filePickerShown = false;
+
 /**
  * Open File Save As dialog and let the user to pick proper file location.
  */
 exports.getTargetFile = function () {
-  return new Promise(resolve => {
+  return new Promise((resolve, reject) => {
+    if (filePickerShown) {
+      reject(null);
+      return;
+    }
+
+    filePickerShown = true;
+
     let fp = Cc["@mozilla.org/filepicker;1"].createInstance(Ci.nsIFilePicker);
 
     let win = getMostRecentBrowserWindow();
     fp.init(win, null, Ci.nsIFilePicker.modeSave);
     fp.appendFilter("JSON Files", "*.json; *.jsonp;");
     fp.appendFilters(Ci.nsIFilePicker.filterText);
     fp.appendFilters(Ci.nsIFilePicker.filterAll);
     fp.filterIndex = 0;
 
     fp.open(rv => {
+      filePickerShown = false;
+
       if (rv == Ci.nsIFilePicker.returnOK || rv == Ci.nsIFilePicker.returnReplace) {
         resolve(fp.file);
       } else {
-        resolve(null);
+        reject(null);
       }
     });
   });
 };
 
 /**
  * Save JSON to a file
  */