diff --git a/glicid/services/parallel.scm b/glicid/services/parallel.scm
index 10074b5..86a930e 100644
--- a/glicid/services/parallel.scm
+++ b/glicid/services/parallel.scm
@@ -51,7 +51,7 @@
                                                                        "-F" "-f" "-M"
                                                                        "-S" #$socket-path
                                                                        "--key-file" #$key-file
-                                                                       "--num-threads" threads)
+                                                                       "--num-threads=" threads)
                                                                  #:log-file #$log-file))
                              (stop #~(make-kill-destructor)))))))