diff --git a/collects/plai/datatype.rkt b/collects/plai/datatype.rkt
index b518049a4e..f5cc2933ac 100644
--- a/collects/plai/datatype.rkt
+++ b/collects/plai/datatype.rkt
@@ -184,7 +184,7 @@
                                                  'variant-field #'field)))
                 ...
                 (define set-variant-field!
-                  (lambda-memocontract (v)
+                  (lambda-memocontract (v nv)
                                        (contract (f:variant? field/c . -> . void)
                                                  set-variant*-field!
                                                  'set-variant-field! 'use
diff --git a/collects/tests/plai/datatype-state.rkt b/collects/tests/plai/datatype-state.rkt
new file mode 100644
index 0000000000..0aff696922
--- /dev/null
+++ b/collects/tests/plai/datatype-state.rkt
@@ -0,0 +1,11 @@
+#lang plai
+(require (prefix-in eli: tests/eli-tester))
+
+(define-type A (a (x number?)))
+
+(define an-a (a 10))
+
+(eli:test
+ (a-x an-a) => 10
+ (set-a-x! an-a 20)
+ (a-x an-a) => 20)
\ No newline at end of file