diff --git a/packages/dsv/test/types.ts b/packages/dsv/test/types.ts
index f48fb7319..54528eef5 100644
--- a/packages/dsv/test/types.ts
+++ b/packages/dsv/test/types.ts
@@ -13,7 +13,17 @@ const config: RollupOptions = {
       include: 'node_modules/**',
       exclude: ['node_modules/foo/**', 'node_modules/bar/**'],
       processRow(row) {
-        return row;
+        return {
+          foo: +row.foo,
+          bar: new Date(row.bar),
+          baz: row.baz === 'true',
+          ...row
+        };
+      }
+    }),
+    dsv({
+      processRow() {
+        // void
       }
     })
   ]
diff --git a/packages/dsv/types/index.d.ts b/packages/dsv/types/index.d.ts
index f923829cd..e1031295a 100644
--- a/packages/dsv/types/index.d.ts
+++ b/packages/dsv/types/index.d.ts
@@ -20,7 +20,7 @@ interface RollupDsvOptions {
    * The function can either manipulate the passed row, or return an entirely new row object.
    * @default undefined
    */
-  processRow?: null | ((row: DSVRowString, id: string) => DSVRowString | undefined);
+  processRow?: null | ((row: DSVRowString, id: string) => object | void);
 }
 
 /**