diff --git a/.github/workflows/code_jsonnet.sh b/.github/workflows/code_jsonnet.sh
index e09a9232..5655ea2d 100644
--- a/.github/workflows/code_jsonnet.sh
+++ b/.github/workflows/code_jsonnet.sh
@@ -5,5 +5,6 @@ for file in $files
 do
   # 'rev | cut | rev' converts "path/to/file.jsonnet" to "path/to/file.json"
   f=$(echo $file | rev | cut -c 4- | rev)
-  jsonnet $file > $f
+  # This is run from the root of the repo.
+  jsonnet --ext-code-file sub="./substation.libsonnet" $file > $f
 done