Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -24,11 +24,12 @@
 
 AX_CHECK_COMPILER_FLAGS(-std=gnu99, [
 	OBJCFLAGS="$OBJCFLAGS -std=gnu99"
 	AC_SUBST(GNU99, "-std=gnu99")
 ])
-AX_CHECK_COMPILER_FLAGS(-fgnu89-inline, [OBJCFLAGS="$OBJCFLAGS -fgnu89-inline"])
+AX_CHECK_COMPILER_FLAGS([-fgnu89-inline -Werror],
+	[OBJCFLAGS="$OBJCFLAGS -fgnu89-inline"])
 AX_CHECK_COMPILER_FLAGS(-pipe, [OBJCFLAGS="$OBJCFLAGS -pipe"])
 AX_CHECK_COMPILER_FLAGS(-fno-common, [OBJCFLAGS="$OBJCFLAGS -fno-common"])
 AX_CHECK_COMPILER_FLAGS(-fno-constant-cfstrings, [
 	OBJCFLAGS="$OBJCFLAGS -fno-constant-cfstrings"
 	AC_SUBST(NO_CONST_CFSTRINGS, "-fno-constant-cfstrings")