diff --git a/README.md b/README.md
index 146ff6d..5e9c3ad 100644
--- a/README.md
+++ b/README.md
@@ -1071,6 +1071,10 @@ List<T> list = ImmutableList.Builder<T>::new;
 sort(list, Comparable::<String>compareTo);
 ````
 
+#### [Header](http://checkstyle.sourceforge.net/config_header.html#Header)
+
+Checks that all `*.java` source files begin with the contents of the `LICENSE.txt` file.
+
 #### [HiddenField](http://checkstyle.sourceforge.net/config_coding.html#HiddenField)
 
 Checks that a local variable or parameter in a method doesn't have the same name as a field. Doesn't apply in constructors or setters.
@@ -2633,14 +2637,6 @@ These checks are not enabled. Notes are included for each explaining why.
 
 Couldn't get my IDE's (IntelliJ) code style to match.
 
-#### [Header](http://checkstyle.sourceforge.net/config_header.html#Header)
-
-> TODO: enable
-
-> TODO: headerFile = LICENSE.txt
-
-> TODO: fileExtensions = java
-
 #### [IllegalInstantiation](http://checkstyle.sourceforge.net/config_coding.html#IllegalInstantiation)
 
 Not really suitable for a template ruleset as it requires an explicit list of classes to apply to.
diff --git a/src/main/resources/net/kemitix/checkstyle.xml b/src/main/resources/net/kemitix/checkstyle.xml
index d6ac91e..4c0fe71 100644
--- a/src/main/resources/net/kemitix/checkstyle.xml
+++ b/src/main/resources/net/kemitix/checkstyle.xml
@@ -86,6 +86,10 @@
 
         <module name="GenericWhitespace"/> <!-- generic tokens are spaced correctly -->
 
+        <module name="Header"> <!-- All java source files start with the contents of LICENSE.txt -->
+            <property name="headerFile" value="LICENSE.txt"/>
+            <property name="fileExtensions" value="java"/>
+        </module>
         <module name="HiddenField">
             <property name="ignoreConstructorParameter" value="true"/>
             <property name="ignoreSetter" value="true"/>