diff --git a/examples/configuration.nix b/examples/configuration.nix
index 65a5f98..f6f293b 100644
--- a/examples/configuration.nix
+++ b/examples/configuration.nix
@@ -245,6 +245,6 @@
   # The nix-bitcoin release version that your config is compatible with.
   # When upgrading to a backwards-incompatible release, nix-bitcoin will display an
   # an error and provide hints for migrating your config to the new release.
-  nix-bitcoin.configVersion = "0.0.41";
+  nix-bitcoin.configVersion = "0.0.49";
 
 }
diff --git a/modules/joinmarket.nix b/modules/joinmarket.nix
index 5bd7e1e..cd4bed0 100644
--- a/modules/joinmarket.nix
+++ b/modules/joinmarket.nix
@@ -27,7 +27,7 @@ let
     rpc_port = ${toString bitcoind.rpc.port}
     rpc_user = ${bitcoind.rpc.users.privileged.name}
     @@RPC_PASSWORD@@
-    ${optionalString (cfg.rpcWalletFile != null) "rpc_wallet_file=${cfg.rpcWalletFile}"}
+    ${optionalString (cfg.rpcWalletFile != null) "rpc_wallet_file = ${cfg.rpcWalletFile}"}
 
     [MESSAGING:server1]
     host = darkirc6tqgpnwd3blln3yfv5ckl47eg7llfxkmtovrv7c7iwohhb6ad.onion
@@ -129,7 +129,7 @@ in {
     };
     rpcWalletFile = mkOption {
       type = types.nullOr types.str;
-      default = null;
+      default = "jm_wallet";
       description = ''
         Name of the watch-only bitcoind wallet the JoinMarket addresses are imported to.
       '';
@@ -244,7 +244,12 @@ in {
             walletname=wallet.jmdat
             wallet=${cfg.dataDir}/wallets/$walletname
             if [[ ! -f $wallet ]]; then
-              echo "Create wallet"
+              ${optionalString (cfg.rpcWalletFile != null) ''
+                echo "Create watch-only wallet ${cfg.rpcWalletFile}"
+                ${bitcoind.cli}/bin/bitcoin-cli -named createwallet \
+                  wallet_name="${cfg.rpcWalletFile}" \
+                  disable_private_keys=true
+              ''}
               pw=$(cat "${secretsDir}"/jm-wallet-password)
               cd ${cfg.dataDir}
               if ! ${nbPkgs.joinmarket}/bin/jm-genwallet --datadir=${cfg.dataDir} $walletname $pw \
diff --git a/modules/versioning.nix b/modules/versioning.nix
index f34eaac..445edf8 100644
--- a/modules/versioning.nix
+++ b/modules/versioning.nix
@@ -91,6 +91,22 @@ let
           rm -f "${secretsDir}"/{lnd-seed-mnemonic,jm-wallet-seed}
       '';
     }
+    {
+      version = "0.0.49";
+      condition = config.services.joinmarket.enable;
+      message = ''
+        Starting with 0.21.0, bitcoind no longer automatically creates and loads a
+        default wallet named `wallet.dat` [1].
+        The joinmarket service now automatically creates a watch-only bitcoind wallet
+        (named by option `services.joinmarket.rpcWalletFile`) when creating a joinmarket wallet.
+
+        If you've used JoinMarket before, add the following to your configuration to
+        continue using the default `wallet.dat` wallet:
+        services.joinmarket.rpcWalletFile = null;
+
+        [1] https://github.com/bitcoin/bitcoin/pull/15454
+      '';
+    }
   ];
 
   incompatibleChanges = optionals