diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5191e0..744e48b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Fix `runTx` silently rolling back after `ROLLBACK TO SAVEPOINT` recovery: clear stale `_transactionException` when PostgreSQL confirms a healthy transaction state.
 - Fix connection permanently blocked when `BEGIN` fails inside `runTx` (stale `_activeTransaction` state).
 - Fix connection left in undefined PostgreSQL state when `ROLLBACK` fails after a transaction error.
+- Fix untyped `Uint8List` parameters being encoded as an integer array literal: they are now encoded as a `bytea` hex literal.
 
 ## 3.5.11
 
diff --git a/lib/src/types/text_codec.dart b/lib/src/types/text_codec.dart
index 81c7c02..dcd19a1 100644
--- a/lib/src/types/text_codec.dart
+++ b/lib/src/types/text_codec.dart
@@ -47,6 +47,10 @@ class PostgresTextEncoder {
       return _encodePoint(input);
     }
 
+    if (input is Uint8List) {
+      return _encodeBytea(input, escapeStrings);
+    }
+
     if (input is List) {
       return _encodeList(input);
     }
@@ -200,6 +204,14 @@ class PostgresTextEncoder {
     return '(${_encodeDouble(value.latitude)}, ${_encodeDouble(value.longitude)})';
   }
 
+  String _encodeBytea(Uint8List value, bool escapeStrings) {
+    final hex = StringBuffer(r'\x');
+    for (final byte in value) {
+      hex.write(byte.toRadixString(16).padLeft(2, '0'));
+    }
+    return _encodeString(hex.toString(), escapeStrings);
+  }
+
   String _encodeList(List value) {
     if (value.isEmpty) {
       return '{}';
diff --git a/test/bytes_example_test.dart b/test/bytes_example_test.dart
index 734357e..4e55195 100644
--- a/test/bytes_example_test.dart
+++ b/test/bytes_example_test.dart
@@ -39,5 +39,28 @@ void main() {
       final bytes = rs2.single.single;
       expect(bytes, [0, 1, 2]);
     });
+
+    test('write and read untyped parameter', () async {
+      final conn = await server.newConnection();
+      await conn.execute('''
+        CREATE TABLE IF NOT EXISTS blobs (
+        id SERIAL PRIMARY KEY,
+        data BYTEA NOT NULL
+        );
+''');
+
+      final data = Uint8List.fromList([0, 1, 127, 255]);
+      final rs1 = await conn.execute(
+        Sql.named('INSERT INTO blobs (data) VALUES (@data) RETURNING id'),
+        parameters: {'data': data},
+      );
+      final id = rs1.single.single;
+
+      final rs2 = await conn.execute(
+        r'SELECT data FROM blobs WHERE id=$1',
+        parameters: [id],
+      );
+      expect(rs2.single.single, data);
+    });
   });
 }
diff --git a/test/encoding_test.dart b/test/encoding_test.dart
index 2c3016b..41007a3 100644
--- a/test/encoding_test.dart
+++ b/test/encoding_test.dart
@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:convert';
+import 'dart:typed_data';
 
 import 'package:postgres/postgres.dart';
 import 'package:postgres/src/types/text_codec.dart';
@@ -954,6 +955,24 @@ void main() {
       );
     });
 
+    test('Encode Uint8List as bytea, not as an int array literal', () {
+      expect(
+        encoder.convert(
+          Uint8List.fromList([0, 1, 127, 255]),
+          escapeStrings: false,
+        ),
+        r'\x00017fff',
+      );
+
+      //  sp   E   '   \   \   x   0   0   f  f   '
+      expect(
+        utf8.encode(encoder.convert(Uint8List.fromList([0, 255]))),
+        equals([32, 69, 39, 92, 92, 120, 48, 48, 102, 102, 39]),
+      );
+
+      expect(encoder.convert(Uint8List(0), escapeStrings: false), r'\x');
+    });
+
     test('Encode DateTime', () {
       // Get users current timezone
       final tz = DateTime(2001, 2, 3).timeZoneOffset;