diff --git a/configure.ac b/configure.ac
index f190672..9862761 100644
--- a/configure.ac
+++ b/configure.ac
@@ -417,7 +417,7 @@
 if test "x$GCC" = "xyes"; then
 	GCC_CFLAGS="-Wall -Wextra -Wno-unused-parameter \
 		-Wno-missing-field-initializers -g -fvisibility=hidden \
-		-Wstrict-prototypes -Wmissing-prototypes"
+		-Wstrict-prototypes -Wmissing-prototypes -Wsign-compare"
 fi
 AC_SUBST(GCC_CFLAGS)