1 files changed, 1 insertions, 0 deletions
diff --git a/ruby.h b/ruby.h
index 9f8ede3e13..f9bb2585f3 100644
--- a/ruby.h
+++ b/ruby.h
@@ -295,6 +295,7 @@ struct RBignum {
 #define RFILE(obj)   (R_CAST(RFile)(obj))
 
 #define FL_SINGLETON FL_USER0
+#define FL_PRIMITIVE FL_USER1
 #define FL_MARK      (1<<8)
 #define FL_FINALIZE  (1<<9)