diff --git a/packages/quicktype-core/src/language/TypeScriptFlow.ts b/packages/quicktype-core/src/language/TypeScriptFlow.ts
index 52b39a581..f21202056 100644
--- a/packages/quicktype-core/src/language/TypeScriptFlow.ts
+++ b/packages/quicktype-core/src/language/TypeScriptFlow.ts
@@ -28,7 +28,7 @@ export const tsFlowOptions = Object.assign({}, javaScriptOptions, {
         "Use string instead of enum for string enums with single value",
         false
     ),
-    preferReadonly: new BooleanOption("prefer-readonly", "Use readonly type members", false)
+    readonly: new BooleanOption("readonly", "Use readonly type members", false)
 });
 
 const tsFlowTypeAnnotations = {
@@ -54,7 +54,7 @@ export abstract class TypeScriptFlowBaseTargetLanguage extends JavaScriptTargetL
             tsFlowOptions.preferUnions,
             tsFlowOptions.preferTypes,
             tsFlowOptions.preferConstValues,
-            tsFlowOptions.preferReadonly
+            tsFlowOptions.readonly
         ];
     }
 
@@ -173,7 +173,7 @@ export abstract class TypeScriptFlowBaseRenderer extends JavaScriptRenderer {
             let propertyName: Sourcelike = name;
             propertyName = modifySource(quotePropertyName, name);
 
-            if (this._tsFlowOptions.preferReadonly) {
+            if (this._tsFlowOptions.readonly) {
                 propertyName = modifySource(_propertyName => "readonly " + _propertyName, propertyName);
             }
 
diff --git a/test/languages.ts b/test/languages.ts
index ffa50b9a1..791485867 100644
--- a/test/languages.ts
+++ b/test/languages.ts
@@ -785,7 +785,7 @@ export const TypeScriptLanguage: Language = {
         ["pokedex.json", { "prefer-types": "true" }],
         { "acronym-style": "pascal" },
         { converters: "all-objects" },
-        { "prefer-readonly": "true" }
+        { readonly: "true" }
     ],
     sourceFiles: ["src/language/TypeScript.ts"]
 };