diff --git a/ape_bsc/ecosystem.py b/ape_bsc/ecosystem.py
index fcdcc55..b9efc8e 100644
--- a/ape_bsc/ecosystem.py
+++ b/ape_bsc/ecosystem.py
@@ -17,9 +17,11 @@
 }
 
 
-def _create_config(block_time: int = 3) -> NetworkConfig:
+def _create_config(block_time: int = 3, **kwargs) -> NetworkConfig:
     return create_network_config(
-        block_time=block_time, default_transaction_type=TransactionType.STATIC
+        block_time=block_time,
+        default_transaction_type=TransactionType.STATIC,
+        **kwargs,
     )
 
 
@@ -30,7 +32,7 @@ class BSCConfig(BaseEthereumConfig):
     testnet: NetworkConfig = _create_config()
 
     # opBNB is really fast, hence the low block time.
-    opbnb: NetworkConfig = _create_config(block_time=1)
+    opbnb: NetworkConfig = _create_config(block_time=1, is_mainnet=True)
     opbnb_testnet: NetworkConfig = _create_config(block_time=1)
 
 
diff --git a/tests/test_ecosystem.py b/tests/test_ecosystem.py
index 50088ac..4aa1d48 100644
--- a/tests/test_ecosystem.py
+++ b/tests/test_ecosystem.py
@@ -55,3 +55,10 @@ def test_encode_transaction(tx_type, bsc, eth_tester_provider):
     address = "0x274b028b03A250cA03644E6c578D81f019eE1323"
     actual = bsc.encode_transaction(address, abi, sender=address, type=tx_type)
     assert actual.gas_limit == eth_tester_provider.max_gas
+
+
+def test_is_mainnet(bsc):
+    assert bsc.mainnet.is_mainnet
+    assert bsc.opbnb.is_mainnet
+    assert not bsc.testnet.is_mainnet
+    assert not bsc.opbnb_testnet.is_mainnet