diff --git a/module/language/tree-il/peval.scm b/module/language/tree-il/peval.scm
index bf96179..25dded4 100644
--- a/module/language/tree-il/peval.scm
+++ b/module/language/tree-il/peval.scm
@@ -1155,6 +1155,25 @@ top-level bindings from ENV and return the resulting expression."
           (simplify-conditional
            (make-conditional src c (for-tail subsequent)
                              (for-tail alternate))))))
+
+      (($ <application> src
+          ($ <primitive-ref> _ '@call-with-values)
+          (($ <lambda> _ _
+              ($ <lambda-case> _
+                 () #f #f #f () ()
+                 ($ <application> _ ($ <primitive-ref> _ 'values)
+                    (produced ...))
+                 #f))
+           ($ <lambda> _ _
+              (and consumer
+                   ($ <lambda-case> _
+                      (? (negate (compose (cute = <> (length produced))
+                                          length)))
+                      #f #f #f () gensyms body #f)))))
+       ;; Producer is (values args ...) but consumer expects a different
+       ;; number of values, which is an error.
+       exp)
+
       (($ <application> src
           ($ <primitive-ref> _ '@call-with-values)
           (producer