diff --git a/lib/puppet/provider/docker_compose/ruby.rb b/lib/puppet/provider/docker_compose/ruby.rb
index b1c1b15f..6576597c 100644
--- a/lib/puppet/provider/docker_compose/ruby.rb
+++ b/lib/puppet/provider/docker_compose/ruby.rb
@@ -66,7 +66,7 @@ def get_image(service_name, compose_services)
       if compose_services[service_name]['extends']
         image = get_image(compose_services[service_name]['extends'], compose_services)
       elsif compose_services[service_name]['build']
-        image = "#{name}_#{service_name}"
+        image = "#{name}-#{service_name}"
       end
     end
     image