diff --git a/00_macros.md b/00_macros.md
index 4d42ff7842aa8c598b120052050637ed1217deac..e56b4aa7bdac810fe70ef5fddedb2243414c7e6a 100644
--- a/00_macros.md
+++ b/00_macros.md
@@ -27,7 +27,7 @@
 \newcommand{\g}{\mathrm{g}}
 \newcommand{\K}{\mathrm{K}}
 \newcommand{\J}{\mathrm{J}}
-\renewcommand{\C}{\mathrm{C}}
+\newcommand{\C}{\mathrm{C}}
 \newcommand{\oC}{^\circ\mathrm{C}}
 \newcommand{\oK}{^\circ\mathrm{K}}
 \newcommand{\A}{\mathrm{A}}