diff --git a/include/etl/private/chrono/day.h b/include/etl/private/chrono/day.h
index b04d3898..8079680d 100644
--- a/include/etl/private/chrono/day.h
+++ b/include/etl/private/chrono/day.h
@@ -146,7 +146,7 @@ namespace etl
 
     private:
 
-      unsigned char value;
+      unsigned value;
     };
 
     //***********************************************************************