diff --git a/docs/sun_checks.xml b/docs/sun_checks.xml
index d8613a678..a54eacdc2 100644
--- a/docs/sun_checks.xml
+++ b/docs/sun_checks.xml
@@ -104,11 +104,14 @@
     <!-- flag reminder comments -->
     <module name="TodoComment"/>
 
-    <!-- length limits -->
+    <!-- enforce default length limits -->
     <module name="LineLength"/>
     <module name="MethodLength"/>
     <module name="FileLength"/>
 
+    <!-- don't allow tabs -->
+    <module name="TabCharacter"/>
+
   </module>
 
   <!-- enforce package documentation -->