diff --git a/templates/extract.yml b/templates/extract.yml
index 2ed6b09a5915e5980067964403f7f275414cf23d..f11060a38f9392a8be0cd9d6304f980e16049d2a 100644
--- a/templates/extract.yml
+++ b/templates/extract.yml
@@ -1,6 +1,10 @@
+variables:
+  # base image used to extract the shell script part from TBC templates
+  TBC_EXTRACT_IMAGE: registry.hub.docker.com/library/alpine
+
 # this job extracts the bash script from the given template(s)
 extract-script:
-  image: registry.hub.docker.com/library/alpine
+  image: $TBC_EXTRACT_IMAGE
   stage: .pre
   script:
     - echo "#!/bin/bash" > script.sh