diff --git a/options/ansi/include/locale.h b/options/ansi/include/locale.h
index 82838927b..66bddea4e 100644
--- a/options/ansi/include/locale.h
+++ b/options/ansi/include/locale.h
@@ -23,6 +23,7 @@
 #define LC_COLLATE_MASK (1<<LC_COLLATE)
 #define LC_MONETARY_MASK (1<<LC_MONETARY)
 #define LC_MESSAGES_MASK (1<<LC_MESSAGES)
+#define LC_MEASUREMENT_MASK (1<<LC_MEASUREMENT)
 #define LC_ALL_MASK 0x7FFFFFFF
 
 #ifdef __cplusplus