diff --git a/lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene90/Lucene90HnswGraphBuilder.java b/lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene90/Lucene90HnswGraphBuilder.java
index 45dbc0cd79e..b59ba3b4a7a 100644
--- a/lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene90/Lucene90HnswGraphBuilder.java
+++ b/lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene90/Lucene90HnswGraphBuilder.java
@@ -38,7 +38,7 @@ import org.apache.lucene.util.hnsw.NeighborQueue;
 public final class Lucene90HnswGraphBuilder {
 
   /** Default random seed for level generation * */
-  private static final long DEFAULT_RAND_SEED = System.currentTimeMillis();
+  private static final long DEFAULT_RAND_SEED = 42;
   /** A name for the HNSW component for the info-stream * */
   public static final String HNSW_COMPONENT = "HNSW";
 
diff --git a/lucene/core/src/java/org/apache/lucene/util/hnsw/HnswGraphBuilder.java b/lucene/core/src/java/org/apache/lucene/util/hnsw/HnswGraphBuilder.java
index 381ac4db2a2..dcd1c25a77f 100644
--- a/lucene/core/src/java/org/apache/lucene/util/hnsw/HnswGraphBuilder.java
+++ b/lucene/core/src/java/org/apache/lucene/util/hnsw/HnswGraphBuilder.java
@@ -36,7 +36,7 @@ import org.apache.lucene.util.InfoStream;
 public final class HnswGraphBuilder {
 
   /** Default random seed for level generation * */
-  private static final long DEFAULT_RAND_SEED = System.currentTimeMillis();
+  private static final long DEFAULT_RAND_SEED = 42;
   /** A name for the HNSW component for the info-stream * */
   public static final String HNSW_COMPONENT = "HNSW";