diff --git a/tests/iotests.cpp b/tests/iotests.cpp
index c19f6ca..26e2ee4 100644
--- a/tests/iotests.cpp
+++ b/tests/iotests.cpp
@@ -568,6 +568,7 @@ void IoTests::testCopyWithNativeFileStream()
     const auto isAborted = [] { return false; };
     const auto callback = [&percentage](double p) { percentage = p; };
     testFile.seekg(0);
+    outputStream.close();
     outputStream.open(outputPath, ios_base::out | ios_base::trunc | ios_base::binary);
     copyHelper.callbackCopy(testFile, outputStream, 50, isAborted, callback);
     CPPUNIT_ASSERT_EQUAL(1.0, percentage);