diff --git a/Makefile b/Makefile
index a5dbc63..3dd1f30 100644
--- a/Makefile
+++ b/Makefile
@@ -90,7 +90,7 @@ browserify:
 		browserify ./ -s markdownit \
 		) > dist/markdown-it.js
 	# Minify
-	uglifyjs dist/markdown-it.js -b beautify=false,ascii-only=true -c -m \
+	uglifyjs dist/markdown-it.js -b beautify=false,ascii_only=true -c -m \
 		--preamble "/*! ${NPM_PACKAGE} ${NPM_VERSION} ${GITHUB_PROJ} @license MIT */" \
 		> dist/markdown-it.min.js
 
diff --git a/package.json b/package.json
index 917dd8a..729ecf6 100644
--- a/package.json
+++ b/package.json
@@ -59,6 +59,6 @@
     "ndoc": "^5.0.0",
     "stylus": "~0.54.2",
     "supertest": "^3.0.0",
-    "uglify-js": "^2.7.3"
+    "uglify-js": "^3.0.18"
   }
 }