diff --git a/rules.mk b/rules.mk
index ed796a54024adc4d4cbcb13d46a03bf6e0c1c8f5..3558f2f0284eb041820623b5fd1e0e02abee80c2 100644
--- a/rules.mk
+++ b/rules.mk
@@ -21,6 +21,7 @@ DUMP:=1
 endif
 
 export TMP_DIR:=$(TOPDIR)/tmp
+export TMPDIR:=$(TMP_DIR)
 
 qstrip=$(strip $(subst ",,$(1)))
 #"))