diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm
index 53437b6..e21492e 100644
--- a/modules/shepherd/service.scm
+++ b/modules/shepherd/service.scm
@@ -717,9 +717,12 @@ otherwise return the number that was read (a PID)."
   (let loop ()
     (catch 'system-error
       (lambda ()
-        (string->number
-         (string-trim-both
-          (call-with-input-file file get-string-all))))
+        (define str
+          (call-with-input-file file get-string-all))
+
+        (local-output (l10n "read-pid-file ~s -> ~s")
+                      file str)
+        (string->number (string-trim-both str)))
       (lambda args
         (let ((errno (system-error-errno args)))
           (if (= ENOENT errno)