diff --git a/doc/coding_standard.txt b/doc/coding_standard.txt
index 0d737a8..95fc364 100644
--- a/doc/coding_standard.txt
+++ b/doc/coding_standard.txt
@@ -15,6 +15,7 @@ must do's:
 		prefer reference over pointer
 		keep implementation in source files with template and constexpr as exceptions
 		keep template/constexpr implementations in .tpp files alongside the .hpp files
+		prefer nullptr over NULL
 	functions:
 		50 max length
 		comments max 2 lines