diff --git a/Makefile b/Makefile
index dd81b13..023f284 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,6 @@
 export PATH := $(HOME)/bin:$(PATH):/usr/local/bin
+IP ?= 127.0.0.1
+PORT ?= 4000
 
 all: serve
 
@@ -6,4 +8,4 @@ stage:
 	bundle exec jekyll build -c '_config.yml,_config.local.yml'
 
 serve:
-	bundle exec jekyll serve -c '_config.yml,_config.local.yml'
+	bundle exec jekyll serve -H "$(IP)" -P "$(PORT)" -c '_config.yml,_config.local.yml'
diff --git a/_config.yml b/_config.yml
index 0383e69..a4635f7 100644
--- a/_config.yml
+++ b/_config.yml
@@ -86,5 +86,6 @@ exclude:
   - README.md
   - CNAME
   - Makefile
+  - .c9
 
 include: [.circleci]