diff --git a/library/Makefile b/library/Makefile
index 098b111..8b2e572 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -2,7 +2,7 @@
 # Also see "include/mbedtls/config.h"
 
 CFLAGS	?= -O2
-WARNING_CFLAGS ?=  -Wall -W
+WARNING_CFLAGS ?=  -Wall -Wextra
 LDFLAGS ?=
 
 LOCAL_CFLAGS = $(WARNING_CFLAGS) -I../include -D_FILE_OFFSET_BITS=64