diff --git a/include/i2c.hpp b/include/i2c.hpp
index 3c5b5f2..7b6afb5 100644
--- a/include/i2c.hpp
+++ b/include/i2c.hpp
@@ -10,7 +10,7 @@
 #include <inttypes.h>
 
 // classname used in logging output
-extern char const* CLASS_NAME;
+extern char const* const CLASS_NAME;
 
 namespace turbopi
 {