diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8bf3345..625dc3e 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -27,13 +27,19 @@ Compile the project and [run the test suite](#testing) to check everything works
 make all
 ```
 
-
 ## Testing
 
 ```shell
 make test
 ```
 
+## Formatting
+
+To format the codebase:
+
+```shell
+make format
+```
 
 ## Releasing
 
diff --git a/Makefile b/Makefile
index c537955..17f8bc5 100644
--- a/Makefile
+++ b/Makefile
@@ -47,4 +47,9 @@ gh-pages: $(REBAR) test doc
 .PHONY: test
 test: $(REBAR) all
 	@$(REBAR) eunit
+	@$(REBAR) fmt --check
 	@$(REBAR) dialyzer
+
+.PHONY: format
+format: build
+	@$(REBAR) fmt
diff --git a/rebar.config b/rebar.config
index 0e6e7e9..b74e041 100644
--- a/rebar.config
+++ b/rebar.config
@@ -31,5 +31,6 @@
 
 {erlfmt, [
     write,
-    {print_width, 140}
+    {print_width, 140},
+    {exclude_files, ["include/DNS-ASN1.hrl", "src/DNS-ASN1.erl"]}
 ]}.