-Werror-implicit-function-declaration \
-fno-common -Wundef -Wno-pointer-sign
+if WINDOWS_NATIVE_BUILD
+# This option is needed to make packed structures work as expected
+# with gcc 4.7+ (mingw) on Windows.
+AM_CFLAGS += -mno-ms-bitfields
+endif
lib_LTLIBRARIES = libwim.la