diff --git a/json-fleece-codegen-util/src/Fleece/CodeGenUtil.hs b/json-fleece-codegen-util/src/Fleece/CodeGenUtil.hs
index 04c6ed8..3df2c97 100644
--- a/json-fleece-codegen-util/src/Fleece/CodeGenUtil.hs
+++ b/json-fleece-codegen-util/src/Fleece/CodeGenUtil.hs
@@ -1797,7 +1797,7 @@ fieldFleeceSchemaCode =
 fleeceFieldFunction :: FleeceSchemaField -> Bool -> HC.HaskellCode
 fleeceFieldFunction field useOptionalNullableBool
   | fieldRequired field = fleeceCoreVar "required"
-  | useOptionalNullableBool = fleeceCoreVar "optionalNullable"
+  | useOptionalNullableBool = fleeceCoreVar "optionalNullable" <> " " <> fleeceCoreVar "OmitKey"
   | otherwise = fleeceCoreVar "optional"
 
 mkFleeceSchemaField ::