diff --git a/doc/coding-style.txt b/doc/coding-style.txt
index 287e9e92..ca70aaee 100644
--- a/doc/coding-style.txt
+++ b/doc/coding-style.txt
@@ -306,6 +306,13 @@ Example:
 2)
 0x1 << y	// Wrong
 
+M17: Avoid forward-declaration of static functions
+==================================================
+
+Functions that are static should not be forward-declared.  The only exception
+to this rule is if a circular dependency condition exists, and the forward
+declaration cannot be avoided.
+
 O1: Shorten the name
 ====================
 Better to use abbreviation, rather than full name, to name a variable,