diff --git a/src/index.rs b/src/index.rs
index 94bafd85cb..a213c1e636 100644
--- a/src/index.rs
+++ b/src/index.rs
@@ -169,6 +169,15 @@ impl<T> BitcoinCoreRpcResultExt<T> for Result<T, bitcoincore_rpc::Error> {
       Err(bitcoincore_rpc::Error::JsonRpc(bitcoincore_rpc::jsonrpc::error::Error::Rpc(
         bitcoincore_rpc::jsonrpc::error::RpcError { code: -8, .. },
       ))) => Ok(None),
+      Err(bitcoincore_rpc::Error::JsonRpc(bitcoincore_rpc::jsonrpc::error::Error::Rpc(
+        bitcoincore_rpc::jsonrpc::error::RpcError {
+          code: -5, message, ..
+        },
+      )))
+        if message.starts_with("No such mempool or blockchain transaction") =>
+      {
+        Ok(None)
+      }
       Err(bitcoincore_rpc::Error::JsonRpc(bitcoincore_rpc::jsonrpc::error::Error::Rpc(
         bitcoincore_rpc::jsonrpc::error::RpcError { message, .. },
       )))
diff --git a/src/subcommand/server.rs b/src/subcommand/server.rs
index 664e0f0830..52dc058986 100644
--- a/src/subcommand/server.rs
+++ b/src/subcommand/server.rs
@@ -7152,4 +7152,14 @@ next
       }
     );
   }
+
+  #[test]
+  fn unknown_output_returns_404() {
+    let server = TestServer::builder().chain(Chain::Regtest).build();
+    server.assert_response(
+      "/output/0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef:123",
+      StatusCode::NOT_FOUND,
+      "output 0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef:123 not found",
+    );
+  }
 }