diff --git a/json-fleece-codegen-util/src/Fleece/CodeGenUtil.hs b/json-fleece-codegen-util/src/Fleece/CodeGenUtil.hs
index 3df2c97..1a71ac0 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" <> " " <> fleeceCoreVar "OmitKey"
+  | useOptionalNullableBool = fleeceCoreVar "optionalNullable" <> " " <> fleeceCoreConstructorVar "OmitKey"
   | otherwise = fleeceCoreVar "optional"
 
 mkFleeceSchemaField ::
@@ -2055,6 +2055,12 @@ fleeceCoreVar =
     . HC.varNameToCodeDefaultQualification
     . HC.toVarName "Fleece.Core" (Just "FC")
 
+fleeceCoreConstructorVar :: HC.FromCode c => T.Text -> c
+fleeceCoreConstructorVar =
+  HC.fromCode
+    . HC.varNameToCodeDefaultQualification
+    . HC.toConstructorVarName "Fleece.Core" (Just "FC")
+
 fleeceCoreFunApp :: HC.FromCode c => T.Text -> T.Text -> c
 fleeceCoreFunApp functionName argument =
   let