diff --git a/package.json b/package.json
index 92e94c0..fa68f27 100644
--- a/package.json
+++ b/package.json
@@ -23,7 +23,7 @@
     "gl": "^4.0.2",
     "http-server": "^0.10.0",
     "mocha": "^3.2.0",
-    "pngjs": "^3.0.0"
+    "pngjs": "^4.0.0"
   },
   "dependencies": {
     "earcut": "^2.1.1",