diff --git a/Makefile b/Makefile
index 72cb5ce..e8405b4 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,7 @@ vtest: flake
 	py.test -s ./tests/
 
 cov cover coverage: flake
-	py.test -s ./tests/ --cov=aiohttp_security --cov=tests --cov-report=xml --cov-report=term
+	py.test -s ./tests/ --cov=aiohttp_security --cov=tests --cov-report=html --cov-report=xml --cov-report=term
 	@echo "open file://`pwd`/coverage/index.html"
 
 clean: