diff --git a/package.json b/package.json
index 01d9abc..be877c7 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,7 @@
   ],
   "dependencies": {},
   "devDependencies": {
-    "chartist": "~0.9.0",
+    "chartist": "~0.9.7",
     "grunt": "^0.4.5",
     "grunt-contrib-clean": "^0.6.0",
     "grunt-contrib-copy": "^0.7.0",
diff --git a/src/scripts/chartist-plugin-zoom.js b/src/scripts/chartist-plugin-zoom.js
index 9936924..faac58b 100644
--- a/src/scripts/chartist-plugin-zoom.js
+++ b/src/scripts/chartist-plugin-zoom.js
@@ -153,7 +153,7 @@
       };
 
       function onMouseUp(event) {
-        if (event.button === 0) {
+        if (event.button === 0 && downPosition) {
           var box = getRect(downPosition, position(event, svg));
           zoomIn(box);          
           downPosition = null;