diff --git a/lucene/test-framework/src/java/org/apache/lucene/index/BaseIndexFileFormatTestCase.java b/lucene/test-framework/src/java/org/apache/lucene/index/BaseIndexFileFormatTestCase.java
index 91432ea9b28..fa33657a7b4 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/index/BaseIndexFileFormatTestCase.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/index/BaseIndexFileFormatTestCase.java
@@ -35,6 +35,7 @@ import org.apache.lucene.codecs.mockrandom.MockRandomPostingsFormat;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.IndexInput;
+import org.apache.lucene.store.MockDirectoryWrapper;
 import org.apache.lucene.util.CloseableThreadLocal;
 import org.apache.lucene.util.InfoStream;
 import org.apache.lucene.util.LuceneTestCase;
@@ -82,7 +83,7 @@ abstract class BaseIndexFileFormatTestCase extends LuceneTestCase {
       this.root = root;
     }
 
-    public long accumulateObject(Object o, long shallowSize, java.util.Map<Field, Object> fieldValues, java.util.Collection<Object> queue) {
+    public long accumulateObject(Object o, long shallowSize, Map<Field, Object> fieldValues, Collection<Object> queue) {
       for (Class<?> clazz = o.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
         if (EXCLUDED_CLASSES.contains(clazz) && o != root) {
           return 0;
@@ -166,6 +167,11 @@ abstract class BaseIndexFileFormatTestCase extends LuceneTestCase {
   /** The purpose of this test is to make sure that bulk merge doesn't accumulate useless data over runs. */
   public void testMergeStability() throws Exception {
     Directory dir = newDirectory();
+    if (dir instanceof MockDirectoryWrapper) {
+      // Else, the virus checker may prevent deletion of files and cause
+      // us to see too many bytes used by extension in the end:
+      ((MockDirectoryWrapper) dir).setEnableVirusScanner(false);
+    }
     // do not use newMergePolicy that might return a MockMergePolicy that ignores the no-CFS ratio
     // do not use RIW which will change things up!
     MergePolicy mp = newTieredMergePolicy();
@@ -184,6 +190,11 @@ abstract class BaseIndexFileFormatTestCase extends LuceneTestCase {
     IndexReader reader = DirectoryReader.open(dir);
 
     Directory dir2 = newDirectory();
+    if (dir2 instanceof MockDirectoryWrapper) {
+      // Else, the virus checker may prevent deletion of files and cause
+      // us to see too many bytes used by extension in the end:
+      ((MockDirectoryWrapper) dir2).setEnableVirusScanner(false);
+    }
     mp = newTieredMergePolicy();
     mp.setNoCFSRatio(0);
     cfg = new IndexWriterConfig(new MockAnalyzer(random())).setUseCompoundFile(false).setMergePolicy(mp);