diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm
index bd7e379..8e7f625 100644
--- a/modules/shepherd/service.scm
+++ b/modules/shepherd/service.scm
@@ -74,6 +74,7 @@
             make-kill-destructor
             exec-command
             fork+exec-command
+            pid-file-default-delay
             read-pid-file
             make-system-constructor
             make-system-destructor
@@ -712,7 +713,12 @@ results."
 set when starting a service."
   (environ))
 
-(define* (read-pid-file file #:key (max-delay 5)
+(define pid-file-default-delay
+  ;; The default number of seconds for which 'read-pid-file' waits for PID
+  ;; files to show up.
+  (make-parameter 5))
+
+(define* (read-pid-file file #:key (max-delay (pid-file-default-delay))
                         (validate-pid? #f))
   "Wait for MAX-DELAY seconds for FILE to show up, and read its content as a
 number.  Return #f if FILE was not created or does not contain a number;