diff --git a/tests/Makefile b/tests/Makefile
index 40ff5b0..d0d9d99 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -3,7 +3,7 @@
 # To compile with PKCS11: add "-lpkcs11-helper" to LDFLAGS
 
 CFLAGS	?= -O2
-WARNING_CFLAGS ?= -Wall -W -Wunused
+WARNING_CFLAGS ?= -Wall -Wextra -Wunused
 LDFLAGS ?=
 
 LOCAL_CFLAGS = $(WARNING_CFLAGS) -I../include -D_FILE_OFFSET_BITS=64