diff --git a/src/csv-loader/loader.test.ts b/src/csv-loader/loader.test.ts
index 2558b3b..bc148f2 100644
--- a/src/csv-loader/loader.test.ts
+++ b/src/csv-loader/loader.test.ts
@@ -497,7 +497,7 @@ describe('parseCsv - type generation', () => {
       currentFilePath: path.join(fixturesDir, 'test.csv'),
     });
 
-    expect(result.typeDefinition).toContain('readonly items: readonly Parts[]');
+    expect(result.typeDefinition).toContain('readonly items: Parts[]');
   });
 
   it('should generate correct type for reference in tuple', () => {
diff --git a/src/csv-loader/loader.ts b/src/csv-loader/loader.ts
index 0d80348..7f741af 100644
--- a/src/csv-loader/loader.ts
+++ b/src/csv-loader/loader.ts
@@ -510,29 +510,29 @@ function schemaToTypeString(schema: Schema, resourceNames?: Map<string, string>)
     case 'reference': {
       const typeName = resourceNames?.get(schema.tableName) ||
         schema.tableName.charAt(0).toUpperCase() + schema.tableName.slice(1);
-      const baseType = schema.isArray ? `readonly ${typeName}[]` : typeName;
+      const baseType = schema.isArray ? `${typeName}[]` : typeName;
       return schema.isOptional ? `${baseType} | null` : baseType;
     }
     case 'array':
       if (schema.element.type === 'tuple') {
         const tupleElements = schema.element.elements.map((el) => {
           const typeStr = schemaToTypeString(el.schema, resourceNames);
-          return el.name ? `readonly ${el.name}: ${typeStr}` : typeStr;
+          return el.name ? `${el.name}: ${typeStr}` : typeStr;
         });
-        return `readonly [${tupleElements.join(', ')}]`;
+        return `[${tupleElements.join(', ')}]`;
       }
       // Wrap union types in parentheses to maintain correct precedence
       const elementType = schemaToTypeString(schema.element, resourceNames);
       if (schema.element.type === 'union') {
-        return `readonly (${elementType})[]`;
+        return `(${elementType})[]`;
       }
-      return `readonly ${elementType}[]`;
+      return `${elementType}[]`;
     case 'tuple':
       const tupleElements = schema.elements.map((el) => {
         const typeStr = schemaToTypeString(el.schema, resourceNames);
-        return el.name ? `readonly ${el.name}: ${typeStr}` : typeStr;
+        return el.name ? `${el.name}: ${typeStr}` : typeStr;
       });
-      return `readonly [${tupleElements.join(', ')}]`;
+      return `[${tupleElements.join(', ')}]`;
     default:
       return 'unknown';
   }
diff --git a/src/type-gen.test.ts b/src/type-gen.test.ts
index 48c6373..4d4ac69 100644
--- a/src/type-gen.test.ts
+++ b/src/type-gen.test.ts
@@ -150,15 +150,15 @@ describe('Type generation for string literals and unions', () => {
           case 'array':
             const elemType = toType(s.element);
             if (s.element.type === 'union') {
-              return `readonly (${elemType})[]`;
+              return `(${elemType})[]`;
             }
-            return `readonly ${elemType}[]`;
+            return `${elemType}[]`;
           case 'tuple':
             const elements = s.elements.map(el => {
               const typeStr = toType(el.schema);
-              return el.name ? `readonly ${el.name}: ${typeStr}` : typeStr;
+              return el.name ? `${el.name}: ${typeStr}` : typeStr;
             });
-            return `readonly [${elements.join(', ')}]`;
+            return `[${elements.join(', ')}]`;
           default: return 'unknown';
         }
       }
@@ -177,19 +177,18 @@ describe('Type generation for string literals and unions', () => {
 
     it('should generate correct type for array of string literals', () => {
       const schema = parseSchema('"item"[]');
-      expect(generateType(schema)).toBe('readonly "item"[]');
+      expect(generateType(schema)).toBe('"item"[]');
     });
 
     it('should generate correct type for array of unions', () => {
       const schema = parseSchema('("pending" | "approved" | "rejected")[]');
       // Union types in arrays need parentheses for correct precedence
-      expect(generateType(schema)).toBe('readonly ("pending" | "approved" | "rejected")[]');
+      expect(generateType(schema)).toBe('("pending" | "approved" | "rejected")[]');
     });
 
     it('should generate correct type for tuple with union field', () => {
       const schema = parseSchema('[name: string; status: "active" | "inactive"]');
-      // Note: tuple elements have readonly modifier
-      expect(generateType(schema)).toBe('readonly [readonly name: string, readonly status: "active" | "inactive"]');
+      expect(generateType(schema)).toBe('[name: string, status: "active" | "inactive"]');
     });
 
     it('should generate correct type for complex union', () => {