diff --git a/server/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java b/server/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java
index a120a640feb..2fdd1f4c99d 100644
--- a/server/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java
+++ b/server/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java
@@ -5131,6 +5131,9 @@ public class InternalEngineTests extends EngineTestCase {
     }
 
     public void testShouldPeriodicallyFlushAfterMerge() throws Exception {
+        engine.close();
+        // Do not use MockRandomMergePolicy as it can cause a force merge performing two merges.
+        engine = createEngine(copy(engine.config(), newMergePolicy(random(), false)));
         assertThat("Empty engine does not need flushing", engine.shouldPeriodicallyFlush(), equalTo(false));
         ParsedDocument doc =
             testParsedDocument(Integer.toString(0), null, testDocumentWithTextField(), SOURCE, null);