diff --git a/linux/linux.mk b/linux/linux.mk
index 7645b5f507..03d89cd204 100644
--- a/linux/linux.mk
+++ b/linux/linux.mk
@@ -150,7 +150,7 @@ endif
 # Disable building host tools with -Werror: newer gcc versions can be
 # extra picky about some code (https://bugs.busybox.net/show_bug.cgi?id=14826)
 LINUX_MAKE_FLAGS = \
-	HOSTCC="$(HOSTCC) $(HOST_CFLAGS) $(HOST_LDFLAGS)" \
+	HOSTCC="$(HOSTCC) $(subst -I/,-isystem /,$(subst -I /,-isystem /,$(HOST_CFLAGS))) $(HOST_LDFLAGS)" \
 	ARCH=$(KERNEL_ARCH) \
 	INSTALL_MOD_PATH=$(TARGET_DIR) \
 	CROSS_COMPILE="$(TARGET_CROSS)" \