diff --git a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
index 3dcbb7962d7..6bfe709ad58 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
@@ -67,6 +67,7 @@ import org.apache.lucene.store.SimpleFSLockFactory;
 import org.apache.lucene.store.SingleInstanceLockFactory;
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.Constants;
 import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.LuceneTestCase;
 import org.apache.lucene.util.SetOnce;
@@ -2374,6 +2375,11 @@ public class TestIndexWriter extends LuceneTestCase {
 
   // LUCENE-5574
   public void testClosingNRTReaderDoesNotCorruptYourIndex() throws IOException {
+
+    // Windows disallows deleting & overwriting files still
+    // open for reading:
+    assumeFalse("this test can't run on Windows", Constants.WINDOWS);
+
     MockDirectoryWrapper dir = newMockDirectory();
 
     // Allow deletion of still open files: