diff --git a/docs/knots/bitcoin.conf b/docs/knots/bitcoin.conf
index a669aac..d23fec1 100644
--- a/docs/knots/bitcoin.conf
+++ b/docs/knots/bitcoin.conf
@@ -2,7 +2,6 @@ chain=regtest
 
 [regtest]
 blockmintxfee=0.0
-fallbackfee=0.0001
 minrelaytxfee=0.0
 mintxfee=0.0
 
@@ -14,3 +13,5 @@ rpcpassword=knots
 rpcuser=knots
 
 txindex=1
+
+walletimplicitsegwit=1
diff --git a/src/DI/Settings.php b/src/DI/Settings.php
index 74d6913..cd51f54 100644
--- a/src/DI/Settings.php
+++ b/src/DI/Settings.php
@@ -58,9 +58,9 @@ public function __construct(array $values)
             $this->bitcoinRpcPass = $values['FAUCET_BITCOIN_RPC_PASS'];
         }
 
-        $this->feeRate = (float) $values['FAUCET_FEE_RATE'] ?: 1.0;
+        $this->feeRate = isset($values['FAUCET_FEE_RATE']) ? (float) $values['FAUCET_FEE_RATE'] : 1.0;
         $this->faucetName = $values['FAUCET_NAME'];
-        $this->mempoolUrl = $values['FAUCET_MEMPOOL_URL'] ?: null;
+        $this->mempoolUrl = $values['FAUCET_MEMPOOL_URL'] ?? null;
         $this->minOneTimeBtc = (float) $values['FAUCET_MIN_ONE_TIME_BTC'];
         $this->maxOneTimeBtc = (float) $values['FAUCET_MAX_ONE_TIME_BTC'];
 
@@ -69,7 +69,7 @@ public function __construct(array $values)
         $this->globalSessionTtl = (int) $values['FAUCET_GLOBAL_SESSION_TTL'];
         $this->globalSessionMaxBtc = '' === $values['FAUCET_GLOBAL_SESSION_MAX_BTC'] ? null : (float) $values['FAUCET_GLOBAL_SESSION_MAX_BTC'];
 
-        $this->passwordBcryptHash = $values['FAUCET_PASSWORD_BCRYPT_HASH'] ?: null;
+        $this->passwordBcryptHash = $values['FAUCET_PASSWORD_BCRYPT_HASH'] ?? null;
         $this->useCaptcha = (bool) $values['FAUCET_USE_CAPTCHA'];
 
         $this->useTxBatching = (bool) $values['FAUCET_USE_BATCHING'];