diff --git a/collects/mzlib/contract.ss b/collects/mzlib/contract.ss
index 55b232f..f0b0a67 100644
--- a/collects/mzlib/contract.ss
+++ b/collects/mzlib/contract.ss
@@ -78,4 +78,5 @@
          name-prop name-pred? name-get
          stronger-prop stronger-pred? stronger-get
          flat-prop flat-pred? flat-get
-         first-order-prop first-order-get)
+         first-order-prop first-order-get
+         (rename-out [or/c union]))