diff --git a/bin/compose-core b/bin/compose-core
index f34aacb..f734605 100755
--- a/bin/compose-core
+++ b/bin/compose-core
@@ -1916,6 +1916,7 @@ get_service_relation() {
     fi
     cat "$cache_file"
 }
+export -f get_service_relation
 
 
 _get_charm_metadata_uses() {