diff --git a/guix-data-service/web/server.scm b/guix-data-service/web/server.scm
index a6a71ca..4a03b5e 100644
--- a/guix-data-service/web/server.scm
+++ b/guix-data-service/web/server.scm
@@ -289,7 +289,7 @@ port. Also, the port used can be changed by passing the --port option.\n"
                                            (list build-id)))))
                                       (delete-background-processing-entries-for-build-ids
                                        conn
-                                       build-id))
+                                       (list build-id)))
                                     build-ids)))))))
                        #:unwind? #t))
                    #:parallel? #t)