diff --git a/module/mes/base-0.mes b/module/mes/base-0.mes
index 7db153e5..727522e6 100644
--- a/module/mes/base-0.mes
+++ b/module/mes/base-0.mes
@@ -63,8 +63,8 @@
                             (if (pair? (cdr (car clauses)))
                                 (if (eq? (car (cdr (car clauses))) '=>)
                                     (append2 (cdr (cdr (car clauses))) '(test))
-                                    (list (cons 'lambda (cons '() (car clauses)))))
-                                (list (cons 'lambda (cons '() (car clauses)))))
+                                    (list (cons 'lambda (cons '() (cons 'test (cdar clauses))))))
+                                (list (cons 'lambda (cons '() (cons 'test (cdar clauses))))))
                             (if (pair? (cdr clauses))
                                 (cons 'cond (cdr clauses)))))))
               (car (car clauses)))))
diff --git a/tests/base.test b/tests/base.test
index 784fe9c4..3ac1e130 100755
--- a/tests/base.test
+++ b/tests/base.test
@@ -61,6 +61,10 @@ exit $?
       (pass-if "cond 2" (seq? (cond (#f)) *unspecified*))
       (pass-if "cond 3" (seq? (cond (#t 0)) 0))
       (pass-if "cond 3" (seq? (cond (#f 1) (#t 0)) 0))
+      (pass-if-equal "cond side effect"
+                     1
+                     (let ((i 0))
+                       (cond ((set! i (1+ i)) i))))
       (pass-if-equal "cond => "
           0 (let ((lst '(0 1 2)))
               (define (next)