diff --git a/ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/sync/backwardsync/ForwardSyncPhaseTest.java b/ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/sync/backwardsync/ForwardSyncPhaseTest.java
index 8581c6d4ff4..1374e54af81 100644
--- a/ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/sync/backwardsync/ForwardSyncPhaseTest.java
+++ b/ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/sync/backwardsync/ForwardSyncPhaseTest.java
@@ -176,6 +176,22 @@ public void shouldDropBlocksThatWeTrust() {
         .isEqualTo(getBlockByNumber(LOCAL_HEIGHT + 2).getHeader());
   }
 
+  @Test
+  public void shouldMergeEvenLongerChains() {
+    final BackwardChain backwardChain = createBackwardChain(LOCAL_HEIGHT - 5, LOCAL_HEIGHT+7);
+    backwardChain.appendExpectedBlock(getBlockByNumber(LOCAL_HEIGHT + 1));
+    final BackwardChain finalChain = createBackwardChain(LOCAL_HEIGHT + 2, LOCAL_HEIGHT + 5);
+    finalChain.prependChain(backwardChain);
+
+    ForwardSyncPhase step = new ForwardSyncPhase(context, finalChain);
+
+    assertThat(finalChain.getFirstAncestorHeader().orElseThrow())
+            .isEqualTo(getBlockByNumber(LOCAL_HEIGHT - 5).getHeader());
+    step.processKnownAncestors(null);
+    assertThat(finalChain.getFirstAncestorHeader().orElseThrow())
+            .isEqualTo(getBlockByNumber(LOCAL_HEIGHT + 2).getHeader());
+  }
+
   @Test
   public void shouldFindBlockWhenRequested() throws Exception {
     ForwardSyncPhase step =