diff --git a/server/src/test/java/org/opensearch/action/search/SearchRequestTests.java b/server/src/test/java/org/opensearch/action/search/SearchRequestTests.java
index 90e154e6e66fc..f475ab7b4a72d 100644
--- a/server/src/test/java/org/opensearch/action/search/SearchRequestTests.java
+++ b/server/src/test/java/org/opensearch/action/search/SearchRequestTests.java
@@ -254,7 +254,9 @@ private SearchRequest mutate(SearchRequest searchRequest) {
         );
         mutators.add(() -> mutation.source(randomValueOtherThan(searchRequest.source(), this::createSearchSourceBuilder)));
         mutators.add(() -> mutation.setCcsMinimizeRoundtrips(searchRequest.isCcsMinimizeRoundtrips() == false));
-        mutators.add(() -> mutation.setPhaseTook(searchRequest.isPhaseTook() == false));
+        mutators.add(
+            () -> mutation.setPhaseTook(searchRequest.isPhaseTook() == null ? randomBoolean() : searchRequest.isPhaseTook() == false)
+        );
         mutators.add(
             () -> mutation.setCancelAfterTimeInterval(
                 searchRequest.getCancelAfterTimeInterval() != null