diff --git a/openwrt/net/mimic/Makefile b/openwrt/net/mimic/Makefile
index 77bba0a..06b5f25 100644
--- a/openwrt/net/mimic/Makefile
+++ b/openwrt/net/mimic/Makefile
@@ -32,6 +32,7 @@ define KernelPackage/mimic
 endef
 
 mimic_kmod_flags := \
+	ccflags-y="-D_MIMIC_KMOD -std=gnu99" \
 	KERNEL_DIR="$(LINUX_DIR)" \
 	ARCH="$(LINUX_KARCH)" \
 	CROSS_COMPILE="$(TARGET_CROSS)" \
@@ -57,7 +58,6 @@ export BPF_CFLAGS := \
 	-D__MIPS$(if $(CONFIG_BIG_ENDIAN),EB,EL)__
 
 define Build/Compile
-	echo "ccflags-y += -std=gnu99" >> "$(PKG_BUILD_DIR)/kmod/Makefile"
 	$(MAKE) -C "$(LINUX_DIR)" $(mimic_kmod_flags) modules
 	$(call Build/Compile/Default,build-cli $(mimic_cli_flags))
 endef