diff --git a/karma.conf.js b/karma.conf.js
index d0a620da5..7c76e82fb 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -17,11 +17,11 @@ module.exports = function(karma) {
 	const grep = args.grep === true ? '' : args.grep;
 	const specPattern = 'test/specs/**/*' + grep + '*.js';
 
-	// Use the same rollup config as our dist files: when debugging (--watch),
+	// Use the same rollup config as our dist files: when debugging (npm run dev),
 	// we will prefer the unminified build which is easier to browse and works
 	// better with source mapping. In other cases, pick the minified build to
 	// make sure that the minification process (terser) doesn't break anything.
-	const regex = args.watch ? /chart\.js$/ : /chart\.min\.js$/;
+	const regex = karma.autoWatch ? /chart\.js$/ : /chart\.min\.js$/;
 	const build = builds.filter(v => v.output.file.match(regex))[0];
 
 	karma.set({