diff --git a/include/host-build.mk b/include/host-build.mk
index c19cb8fd1..5670b6f17 100644
--- a/include/host-build.mk
+++ b/include/host-build.mk
@@ -4,7 +4,26 @@
 # This is free software, licensed under the GNU General Public License v2.
 # See /LICENSE for more information.
 #
-OS:=$(shell uname)
+
+include $(TOPDIR)/.host.mk
+
+$(TOPDIR)/.host.mk: $(INCLUDE_DIR)/host-build.mk
+	echo "HOST_OS:=`uname`" > $@
+	echo "HOST_ARCH:=` \
+		$(HOSTCC) -dumpmachine | sed -e s'/-.*//' \
+			-e 's/sparc.*/sparc/' \
+			-e 's/arm.*/arm/' \
+			-e 's/m68k.*/m68k/' \
+			-e 's/ppc/powerpc/' \
+			-e 's/v850.*/v850/' \
+			-e 's/sh[234]/sh/' \
+			-e 's/mips-.*/mips/' \
+			-e 's/mipsel-.*/mipsel/' \
+			-e 's/cris.*/cris/' \
+			-e 's/i[3-9]86/i386/'`" >> $@
+	echo "GNU_HOST_NAME:=`$(HOSTCC) -dumpmachine`" >> $@
+
+
 ifneq ($(strip $(PKG_CAT)),)
   ifeq ($(PKG_CAT),unzip)
     UNPACK=unzip -d $(PKG_BUILD_DIR) $(DL_DIR)/$(PKG_SOURCE)
diff --git a/rules.mk b/rules.mk
index 0ec5daf08..84163ba22 100644
--- a/rules.mk
+++ b/rules.mk
@@ -64,21 +64,6 @@ ifneq ($(CONFIG_CCACHE),)
   TARGET_CC:= ccache $(TARGET_CC)
 endif
 
-HOST_ARCH:=$(shell $(HOSTCC) -dumpmachine | sed -e s'/-.*//' \
-	-e 's/sparc.*/sparc/' \
-	-e 's/arm.*/arm/' \
-	-e 's/m68k.*/m68k/' \
-	-e 's/ppc/powerpc/' \
-	-e 's/v850.*/v850/' \
-	-e 's/sh[234]/sh/' \
-	-e 's/mips-.*/mips/' \
-	-e 's/mipsel-.*/mipsel/' \
-	-e 's/cris.*/cris/' \
-	-e 's/i[3-9]86/i386/' \
-	)
-
-GNU_HOST_NAME:=$(shell $(HOSTCC) -dumpmachine)
-
 TARGET_CONFIGURE_OPTS:= \
   AR=$(TARGET_CROSS)ar \
   AS="$(TARGET_CC) -c $(TARGET_CFLAGS)" \