diff --git a/src/Makefile.am b/src/Makefile.am
index a96168c..cbc1019 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,6 +1,6 @@
 lib_LTLIBRARIES         = libeditline.la
 libeditline_la_SOURCES  = editline.c editline.h complete.c sysunix.c unix.h
 libeditline_la_CFLAGS   = -std=gnu99
-libeditline_la_CFLAGS  += -W -Wall -Wundef -Wunused -Wstrict-prototypes
+libeditline_la_CFLAGS  += -W -Wall -Wextra -Wundef -Wunused -Wstrict-prototypes
 libeditline_la_CFLAGS  += -Werror-implicit-function-declaration -Wshadow -Wcast-qual
 libeditline_la_LDFLAGS  = $(AM_LDFLAGS) -version-info 0:0:0