diff --git a/include/types/h1.h b/include/types/h1.h
index ec8cca0..2dd58dd 100644
--- a/include/types/h1.h
+++ b/include/types/h1.h
@@ -139,6 +139,7 @@
 #define H1_MF_CLEN              0x00000001 // content-length present
 #define H1_MF_CHNK              0x00000002 // chunk present, exclusive with c-l
 #define H1_MF_RESP              0x00000004 // this message is the response message
+#define H1_MF_TOLOWER           0x00000008 // turn the header names to lower case
 
 
 /* basic HTTP/1 message state for use in parsers. The err_pos field is special,