diff --git a/debian/rules b/debian/rules
index 45f1e63..6f3ef8c 100755
--- a/debian/rules
+++ b/debian/rules
@@ -1,18 +1,15 @@
 #!/usr/bin/make -f
 
 export DESTDIR = debian/tmp
-export VENDOR ?= 1
 
 %:
 	dh $@
 
 override_dh_auto_clean:
-	if ! ischroot && test "${VENDOR}" = "1"; then \
-		just vendor; \
-	fi
+	ischroot || just vendor
 
 override_dh_auto_build:
-	just build-vendored
+	test -e vendor.tar && just build-vendored || just
 
 override_dh_auto_install:
 	just rootdir=$(DESTDIR) install