diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 6e6555c7a..5ffa71d21 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -38,6 +38,7 @@ Code must be written in the
 always be used for code blocks, even one-liners.
 
 Names should use underscores, not camel case, with class/struct names ending in `_t`.
+Template parameters must use all upper case.
 
 Headers should be included in the order `config.h`, C++ standard library headers,
 C library headers, Boost headers, and last osm2pgsql files.