diff --git a/guix/scripts/git.scm b/guix/scripts/git.scm
index 8fcd0ccca8..3b141a622d 100644
--- a/guix/scripts/git.scm
+++ b/guix/scripts/git.scm
@@ -18,18 +18,26 @@
 
 (define-module (guix scripts git)
   #:use-module (ice-9 match)
+  #:use-module (ice-9 format)
   #:use-module (guix ui)
   #:use-module (guix scripts)
+  #:use-module (srfi srfi-1)
   #:export (guix-git))
 
+(define %sub-commands
+  `(("authenticate" . "verify commit signatures and authorizations")
+    ("log". "show Git commit history")))
+
 (define (show-help)
   (display (G_ "Usage: guix git COMMAND ARGS...
 Operate on Git repositories.\n"))
   (newline)
   (display (G_ "The valid values for ACTION are:\n"))
   (newline)
-  (display (G_ "\
-   authenticate    verify commit signatures and authorizations\n"))
+  (for-each (match-lambda
+              ((name . help)
+               (format #t "~13a ~a\n" name help)))
+            %sub-commands)
   (newline)
   (display (G_ "
   -h, --help             display this help and exit"))
@@ -38,8 +46,6 @@ Operate on Git repositories.\n"))
   (newline)
   (show-bug-report-information))
 
-(define %sub-commands '("authenticate" "log"))
-
 (define (resolve-sub-command name)
   (let ((module (resolve-interface
                  `(guix scripts git ,(string->symbol name))))
@@ -61,7 +67,6 @@ Operate on Git repositories.\n"))
       ((or ("-V") ("--version"))
        (show-version-and-exit "guix git"))
       ((sub-command args ...)
-       (if (member sub-command %sub-commands)
+       (if (find (lambda (s) (string=? (first s) sub-command)) %sub-commands)
            (apply (resolve-sub-command sub-command) args)
-           (format (current-error-port)
-                   (G_ "guix git: invalid sub-command~%")))))))
+           (leave (G_ "~a: invalid sub-command~%") sub-command))))))