diff --git a/CHANGELOG.md b/CHANGELOG.md
index fa99e9abd5a..7a125cb2501 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - Introduce a cap to reputation score increase [#4230](https://github.com/hyperledger/besu/pull/4230)
 - Add experimental CLI option for `--Xp2p-peer-lower-bound` [#4200](https://github.com/hyperledger/besu/pull/4200)
 - Improve pending blocks retrieval mechanism [#4227](https://github.com/hyperledger/besu/pull/4227)
+- set mainnet terminal total difficulty [#4260](https://github.com/hyperledger/besu/pull/4260)
 
 ### Bug Fixes
 - Fixes off-by-one error for mainnet TTD fallback [#4223](https://github.com/hyperledger/besu/pull/4223)
diff --git a/besu/src/test/java/org/hyperledger/besu/RunnerTest.java b/besu/src/test/java/org/hyperledger/besu/RunnerTest.java
index d9221d0f472..5510419614f 100644
--- a/besu/src/test/java/org/hyperledger/besu/RunnerTest.java
+++ b/besu/src/test/java/org/hyperledger/besu/RunnerTest.java
@@ -403,6 +403,8 @@ private GenesisConfigFile getFastSyncGenesis() {
         (node) -> {
           // Clear DAO block so that inability to validate DAO block won't interfere with fast sync
           node.remove("daoForkBlock");
+          // remove merge terminal difficulty for fast sync in the absence of a CL mock
+          node.remove("terminalTotalDifficulty");
         });
     return GenesisConfigFile.fromConfig(jsonNode);
   }
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 984b412354e..1b64a1cdb65 100644
--- a/besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java
+++ b/besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java
@@ -3670,6 +3670,8 @@ public void blockProducingOptionsWarnsMinerShouldBeEnabled() {
 
     final Address requestedCoinbase = Address.fromHexString("0000011111222223333344444");
     parseCommand(
+        "--network",
+        "dev",
         "--miner-coinbase",
         requestedCoinbase.toString(),
         "--min-gas-price",
@@ -3692,7 +3694,8 @@ public void blockProducingOptionsWarnsMinerShouldBeEnabledToml() throws IOExcept
     final Path toml =
         createTempFile(
             "toml",
-            "miner-coinbase=\""
+            "network=\"dev\"\n"
+                + "miner-coinbase=\""
                 + requestedCoinbase
                 + "\"\n"
                 + "min-gas-price=42\n"
@@ -3735,7 +3738,7 @@ public void blockProducingOptionsDoNotWarnWhenMergeEnabled() {
 
   @Test
   public void minGasPriceRequiresMainOption() {
-    parseCommand("--min-gas-price", "0");
+    parseCommand("--min-gas-price", "0", "--network", "dev");
 
     verifyOptionsConstraintLoggerCall("--miner-enabled", "--min-gas-price");
 
@@ -3745,7 +3748,7 @@ public void minGasPriceRequiresMainOption() {
 
   @Test
   public void minGasPriceRequiresMainOptionToml() throws IOException {
-    final Path toml = createTempFile("toml", "min-gas-price=0\n");
+    final Path toml = createTempFile("toml", "min-gas-price=0\nnetwork=\"dev\"\n");
 
     parseCommand("--config-file", toml.toString());
 
diff --git a/config/src/main/resources/mainnet.json b/config/src/main/resources/mainnet.json
index 805a668c762..57273c6436f 100644
--- a/config/src/main/resources/mainnet.json
+++ b/config/src/main/resources/mainnet.json
@@ -13,6 +13,7 @@
     "londonBlock": 12965000,
     "arrowGlacierBlock": 13773000,
     "grayGlacierBlock": 15050000,
+    "terminalTotalDifficulty": 58750000000000000000000,
     "ethash": {
     },
     "discovery": {
diff --git a/config/src/test/java/org/hyperledger/besu/config/GenesisConfigFileTest.java b/config/src/test/java/org/hyperledger/besu/config/GenesisConfigFileTest.java
index 3112f908377..55efdcb1635 100644
--- a/config/src/test/java/org/hyperledger/besu/config/GenesisConfigFileTest.java
+++ b/config/src/test/java/org/hyperledger/besu/config/GenesisConfigFileTest.java
@@ -228,6 +228,17 @@ public void assertGoerliTerminalTotalDifficulty() {
         .isEqualTo(UInt256.valueOf(new BigInteger("10790000")));
   }
 
+  @Test
+  public void assertMainnetTerminalTotalDifficulty() {
+    GenesisConfigOptions mainnetOptions =
+        GenesisConfigFile.genesisFileFromResources("/mainnet.json").getConfigOptions();
+
+    assertThat(mainnetOptions.getTerminalTotalDifficulty()).isPresent();
+    // tentative as of 2022-08-11:
+    assertThat(mainnetOptions.getTerminalTotalDifficulty().get())
+        .isEqualTo(UInt256.valueOf(new BigInteger("58750000000000000000000")));
+  }
+
   @Test
   public void assertTerminalTotalDifficultyOverride() {
     GenesisConfigOptions ropstenOverrideOptions =