diff --git a/2013/birken/Makefile b/2013/birken/Makefile
index 02930f403..d7d71173a 100644
--- a/2013/birken/Makefile
+++ b/2013/birken/Makefile
@@ -39,7 +39,7 @@ include ../../var.mk
 # Common C compiler warnings to silence
 #
 CSILENCE= -Wno-newline-eof -Wno-strict-prototypes -Wno-maybe-uninitialized \
-	  -Wno-misleading-indentation
+	  -Wno-misleading-indentation -Wno-documentation
 
 # Attempt to silence unknown warnings
 #