diff --git a/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestNRTReplication.java b/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestNRTReplication.java
index 2af7a68bdb6..e530652817b 100644
--- a/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestNRTReplication.java
+++ b/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestNRTReplication.java
@@ -104,6 +104,7 @@ public class TestNRTReplication extends LuceneTestCase {
     long seed = random().nextLong() * nodeStartCounter.incrementAndGet();
     cmd.add("-Dtests.seed=" + SeedUtils.formatSeed(seed));
     cmd.add("-ea");
+    cmd.add("-Djava.io.tmpdir=" + childTempDir.toFile());
 
     cmd.addAll(getJvmForkArguments());
 
diff --git a/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestStressNRTReplication.java b/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestStressNRTReplication.java
index c2e6c5d89fc..f1480c6ffb8 100644
--- a/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestStressNRTReplication.java
+++ b/lucene/replicator/src/test/org/apache/lucene/replicator/nrt/TestStressNRTReplication.java
@@ -608,6 +608,7 @@ public class TestStressNRTReplication extends LuceneTestCase {
     long seed = random().nextLong() * nodeStartCounter.incrementAndGet();
     cmd.add("-Dtests.seed=" + SeedUtils.formatSeed(seed));
     cmd.add("-ea");
+    cmd.add("-Djava.io.tmpdir=" + childTempDir.toFile());
     cmd.addAll(getJvmForkArguments());
     cmd.add("org.junit.runner.JUnitCore");
     cmd.add(TestSimpleServer.class.getName());