diff --git a/allways/chain_providers/bitcoin.py b/allways/chain_providers/bitcoin.py
index da9315bb..2da06281 100644
--- a/allways/chain_providers/bitcoin.py
+++ b/allways/chain_providers/bitcoin.py
@@ -400,9 +400,19 @@ def is_valid_address(self, address: str) -> bool:
         try:
             if address.lower().startswith(('bc1', 'tb1', 'bcrt1')):
                 hrp, data = bech32.bech32_decode(address)
-                return data is not None
+                if data is None:
+                    return False
+                if self.network == 'testnet':
+                    return hrp == 'tb'
+                if self.network == 'regtest':
+                    return hrp == 'bcrt'
+                return hrp == 'bc'
             decoded = base58.b58decode_check(address)
-            return len(decoded) == 21 and decoded[0] in (0x00, 0x05, 0x6F, 0xC4)
+            if len(decoded) != 21:
+                return False
+            if self.network in ('testnet', 'regtest'):
+                return decoded[0] in (0x6F, 0xC4)
+            return decoded[0] in (0x00, 0x05)
         except Exception:
             return False
 
diff --git a/tests/test_bitcoin_signing.py b/tests/test_bitcoin_signing.py
index e174f42e..d45aba98 100644
--- a/tests/test_bitcoin_signing.py
+++ b/tests/test_bitcoin_signing.py
@@ -112,6 +112,42 @@ def make_lightweight_provider() -> BitcoinProvider:
         return BitcoinProvider()
 
 
+def make_lightweight_provider_for_network(network: str) -> BitcoinProvider:
+    with patch.dict(
+        os.environ, {'BTC_MODE': 'lightweight', 'BTC_NETWORK': network, 'BTC_PRIVATE_KEY': TEST_WIF}, clear=False
+    ):
+        return BitcoinProvider()
+
+
+class TestBitcoinAddressValidationNetwork:
+    MAINNET_ADDRESSES = [
+        'bc1q6tvmnmetj8vfz98vuetpvtuplqtj4uvvwjgxxc',
+        '1LDsjB43N2NAQ1Vbc2xyHca4iBBciN8iwC',
+        '37XAVCtKEvPbx2rpkxx7FmrUsetFXSawx5',
+    ]
+    TESTNET_ADDRESSES = [
+        'tb1q6tvmnmetj8vfz98vuetpvtuplqtj4uvvy5n4at',
+        'mzjq2E92B3oRB7yDKbwM7XnPaAnKfRERw2',
+        '2My5NYwpLrNtx9pVNS6Zysiqk616RJuHDuz',
+    ]
+
+    def test_mainnet_accepts_mainnet_addresses(self):
+        provider = make_lightweight_provider_for_network('mainnet')
+        assert all(provider.is_valid_address(addr) for addr in self.MAINNET_ADDRESSES)
+
+    def test_mainnet_rejects_testnet_addresses(self):
+        provider = make_lightweight_provider_for_network('mainnet')
+        assert all(not provider.is_valid_address(addr) for addr in self.TESTNET_ADDRESSES)
+
+    def test_testnet_accepts_testnet_addresses(self):
+        provider = make_lightweight_provider_for_network('testnet')
+        assert all(provider.is_valid_address(addr) for addr in self.TESTNET_ADDRESSES)
+
+    def test_testnet_rejects_mainnet_addresses(self):
+        provider = make_lightweight_provider_for_network('testnet')
+        assert all(not provider.is_valid_address(addr) for addr in self.MAINNET_ADDRESSES)
+
+
 class TestBitcoinProviderSignFromProof:
     """Direct coverage of BitcoinProvider.sign_from_proof — the wrapper our
     validator/CLI actually invoke, not the underlying library."""