diff --git a/Dockerfile b/Dockerfile
index c68e927..3beb40a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -39,3 +39,6 @@ EOF
 
 WORKDIR /source
 ENTRYPOINT ["/run-bookml"]
+
+# reset TMPDIR to usual value or biber will not work
+ENV TMPDIR=/tmp