diff --git a/uncanny/debian/rules b/uncanny/debian/rules
index e9eb707..59f6936 100755
--- a/uncanny/debian/rules
+++ b/uncanny/debian/rules
@@ -11,6 +11,8 @@ export DH_GOPKG = git.kabelsalat.ch/ccc-basel/matemat
 # use module mode and enable internet access
 export GO111MODULE = on
 export GOPROXY =
+# this is needed for building on buster, but should be dropped on bullseye
+export GOCACHE = cache
 
 %:
 	dh $@ --builddirectory=_build --buildsystem=golang --with=golang