diff --git a/guix/git-authenticate.scm b/guix/git-authenticate.scm
index 00d22ef479f..c3337171364 100644
--- a/guix/git-authenticate.scm
+++ b/guix/git-authenticate.scm
@@ -184,8 +184,11 @@ to remove '.guix-authorizations' file")
               default-authorizations)
             (throw key error)))))
 
-  (apply lset-intersection bytevector=?
-         (map commit-authorizations (commit-parents commit))))
+  (match (commit-parents commit)
+    (() default-authorizations)
+    (parents
+     (apply lset-intersection bytevector=?
+            (map commit-authorizations parents)))))
 
 (define* (authenticate-commit repository commit keyring
                               #:key (default-authorizations '()))