diff --git a/CHANGELOG.md b/CHANGELOG.md
index c44f403c8..4da5b2ab6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Additions and Improvements
 - Avoid sending added block events to transaction pool, and processing incoming transactions during initial sync [#4457](https://github.com/hyperledger/besu/pull/4457)
 - When building a new proposal, keep the best block built until now instead of the last one [#4455](https://github.com/hyperledger/besu/pull/4455)
+- Add Mainnet to merged networks [#4463](https://github.com/hyperledger/besu/pull/4463)
 
 ### Bug Fixes
 ### Download Links
diff --git a/besu/src/main/java/org/hyperledger/besu/cli/config/NetworkName.java b/besu/src/main/java/org/hyperledger/besu/cli/config/NetworkName.java
index 5505a0853..1cf24da84 100644
--- a/besu/src/main/java/org/hyperledger/besu/cli/config/NetworkName.java
+++ b/besu/src/main/java/org/hyperledger/besu/cli/config/NetworkName.java
@@ -89,6 +89,7 @@ public enum NetworkName {
 
   public static boolean isMergedNetwork(final NetworkName networkName) {
     switch (networkName) {
+      case MAINNET:
       case GOERLI:
       case ROPSTEN:
       case SEPOLIA:
diff --git a/besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java b/besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java
index 400951449..367345ab2 100644
--- a/besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java
+++ b/besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java
@@ -882,7 +882,7 @@ public class BesuCommandTest extends CommandTestAbstract {
 
     final SynchronizerConfiguration syncConfig = syncConfigurationCaptor.getValue();
     assertThat(syncConfig.getSyncMode()).isEqualTo(SyncMode.FAST);
-    assertThat(syncConfig.getFastSyncMinimumPeerCount()).isEqualTo(5);
+    assertThat(syncConfig.getFastSyncMinimumPeerCount()).isEqualTo(1);
 
     assertThat(commandErrorOutput.toString(UTF_8)).isEmpty();
 
@@ -1709,19 +1709,19 @@ public class BesuCommandTest extends CommandTestAbstract {
   }
 
   @Test
-  public void checkValidDefaultFastSyncMinPeersOption() {
-    parseCommand("--sync-mode", "FAST");
+  public void checkValidDefaultFastSyncMinPeersPoS() {
+    parseCommand("--sync-mode", "FAST", "--network", "MAINNET");
     verify(mockControllerBuilder).synchronizerConfiguration(syncConfigurationCaptor.capture());
 
     final SynchronizerConfiguration syncConfig = syncConfigurationCaptor.getValue();
     assertThat(syncConfig.getSyncMode()).isEqualTo(SyncMode.FAST);
-    assertThat(syncConfig.getFastSyncMinimumPeerCount()).isEqualTo(5);
+    assertThat(syncConfig.getFastSyncMinimumPeerCount()).isEqualTo(1);
     assertThat(commandOutput.toString(UTF_8)).isEmpty();
     assertThat(commandErrorOutput.toString(UTF_8)).isEmpty();
   }
 
   @Test
-  public void checkValidDefaultFastSyncMinPeersPreMergeOption() {
+  public void checkValidDefaultFastSyncMinPeersPoW() {
     parseCommand("--sync-mode", "FAST", "--network", "CLASSIC");
     verify(mockControllerBuilder).synchronizerConfiguration(syncConfigurationCaptor.capture());
 
@@ -1732,18 +1732,6 @@ public class BesuCommandTest extends CommandTestAbstract {
     assertThat(commandErrorOutput.toString(UTF_8)).isEmpty();
   }
 
-  @Test
-  public void checkValidDefaultFastSyncMinPeersPostMergeOption() {
-    parseCommand("--sync-mode", "FAST", "--network", "GOERLI");
-    verify(mockControllerBuilder).synchronizerConfiguration(syncConfigurationCaptor.capture());
-
-    final SynchronizerConfiguration syncConfig = syncConfigurationCaptor.getValue();
-    assertThat(syncConfig.getSyncMode()).isEqualTo(SyncMode.FAST);
-    assertThat(syncConfig.getFastSyncMinimumPeerCount()).isEqualTo(1);
-    assertThat(commandOutput.toString(UTF_8)).isEmpty();
-    assertThat(commandErrorOutput.toString(UTF_8)).isEmpty();
-  }
-
   @Test
   public void parsesValidFastSyncMinPeersOption() {
     parseCommand("--sync-mode", "FAST", "--fast-sync-min-peers", "11");