diff --git a/gash/pattern.scm b/gash/pattern.scm
index a8c17e5..a6e825d 100644
--- a/gash/pattern.scm
+++ b/gash/pattern.scm
@@ -234,11 +234,14 @@ source string is the only string that will match it."
      ((string-ends-with-part s part start i) (- i (vector-length part)))
      (else (loop (1- i))))))
 
-(define* (pattern-match? pattern str #:optional (start 0)
-                         (end (string-length str))
-                         #:key explicit-initial-period?)
+(define* (pattern-match? pattern str #:key explicit-initial-period?)
   "Check if @var{str} matches @var{pattern}."
 
+  ;; XXX: These used to be optional arguments, but Mes handles mixing
+  ;; optional and keyword arguments differently than Guile.
+  (define start 0)
+  (define end (string-length str))
+
   (define (parts-match? parts start)
     (match parts
       (() (= start end))
@@ -255,8 +258,7 @@ source string is the only string that will match it."
              (char=? (string-ref str start) #\.))
         (match parts
           ((#(#\. _ ...) . _)
-           (pattern-match? pattern str start end
-                           #:explicit-initial-period? #f))
+           (pattern-match? pattern str #:explicit-initial-period? #f))
           (_ #f))
         (match parts
           (() (= start end))