diff --git a/SDL3-CS/ConstantAttribute.cs b/SDL3-CS/ConstantAttribute.cs
new file mode 100644
index 0000000..9dce031
--- /dev/null
+++ b/SDL3-CS/ConstantAttribute.cs
@@ -0,0 +1,17 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Diagnostics;
+
+namespace SDL
+{
+    /// <summary>
+    /// Denotes a manually defined constant.
+    /// Such consants should be excluded from ClangSharp generation to prevent warnings or duplicate definitions.
+    /// Handled by <c>get_manually_written_symbols()</c> in generate_bindings.py.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Field)]
+    [Conditional("NEVER")]
+    public class ConstantAttribute : Attribute;
+}
diff --git a/SDL3-CS/SDL3/ClangSharp/SDL_pen.g.cs b/SDL3-CS/SDL3/ClangSharp/SDL_pen.g.cs
index effec96..a2dabb4 100644
--- a/SDL3-CS/SDL3/ClangSharp/SDL_pen.g.cs
+++ b/SDL3-CS/SDL3/ClangSharp/SDL_pen.g.cs
@@ -94,9 +94,6 @@ namespace SDL
         [NativeTypeName("#define SDL_PEN_INVALID ((SDL_PenID)0)")]
         public const SDL_PenID SDL_PEN_INVALID = ((SDL_PenID)(0));
 
-        [NativeTypeName("#define SDL_PEN_MOUSEID ((SDL_MouseID)-2)")]
-        public const SDL_MouseID SDL_PEN_MOUSEID = ((SDL_MouseID)(-2));
-
         [NativeTypeName("#define SDL_PEN_INFO_UNKNOWN (-1)")]
         public const int SDL_PEN_INFO_UNKNOWN = (-1);
 
diff --git a/SDL3-CS/SDL3/ClangSharp/SDL_touch.g.cs b/SDL3-CS/SDL3/ClangSharp/SDL_touch.g.cs
index 5aee4bb..777f015 100644
--- a/SDL3-CS/SDL3/ClangSharp/SDL_touch.g.cs
+++ b/SDL3-CS/SDL3/ClangSharp/SDL_touch.g.cs
@@ -63,11 +63,5 @@ namespace SDL
 
         [DllImport("SDL3", CallingConvention = CallingConvention.Cdecl, ExactSpelling = true)]
         public static extern SDL_Finger* SDL_GetTouchFinger(SDL_TouchID touchID, int index);
-
-        [NativeTypeName("#define SDL_TOUCH_MOUSEID ((SDL_MouseID)-1)")]
-        public const SDL_MouseID SDL_TOUCH_MOUSEID = ((SDL_MouseID)(-1));
-
-        [NativeTypeName("#define SDL_MOUSE_TOUCHID ((SDL_TouchID)-1)")]
-        public const SDL_TouchID SDL_MOUSE_TOUCHID = ((SDL_TouchID)(-1));
     }
 }
diff --git a/SDL3-CS/SDL3/SDL_pen.cs b/SDL3-CS/SDL3/SDL_pen.cs
index 2848637..ec3da99 100644
--- a/SDL3-CS/SDL3/SDL_pen.cs
+++ b/SDL3-CS/SDL3/SDL_pen.cs
@@ -7,4 +7,10 @@ namespace SDL
 {
     [Typedef]
     public enum SDL_PenID : UInt32;
+
+    public static partial class SDL3
+    {
+        [Constant]
+        public const SDL_MouseID SDL_PEN_MOUSEID = unchecked((SDL_MouseID)(-2));
+    }
 }
diff --git a/SDL3-CS/SDL3/SDL_touch.cs b/SDL3-CS/SDL3/SDL_touch.cs
index d3f473e..b07724f 100644
--- a/SDL3-CS/SDL3/SDL_touch.cs
+++ b/SDL3-CS/SDL3/SDL_touch.cs
@@ -10,4 +10,13 @@ namespace SDL
 
     [Typedef]
     public enum SDL_TouchID : UInt64;
+
+    public static partial class SDL3
+    {
+        [Constant]
+        public const SDL_MouseID SDL_TOUCH_MOUSEID = unchecked((SDL_MouseID)(-1));
+
+        [Constant]
+        public const SDL_TouchID SDL_MOUSE_TOUCHID = unchecked((SDL_TouchID)(-1));
+    }
 }
diff --git a/SDL3-CS/generate_bindings.py b/SDL3-CS/generate_bindings.py
index 8e34780..834f085 100644
--- a/SDL3-CS/generate_bindings.py
+++ b/SDL3-CS/generate_bindings.py
@@ -166,6 +166,21 @@ def check_generated_functions(sdl_api, header, generated_file_paths):
             print(f"[⚠️ Warning] Function {name} not found in generated files:", *generated_file_paths)
 
 
+defined_constant_regex = re.compile(r"\[Constant]\s*public (const|static readonly) \w+ (SDL_\w+) = ", re.MULTILINE)
+
+
+def get_manually_written_symbols(header):
+    """Returns symbols names whose definitions are manually written in C#."""
+    cs_file = header.cs_file()
+    if cs_file.is_file():
+        with open(cs_file, "r", encoding="utf-8") as f:
+            text = f.read()
+            for match in defined_constant_regex.finditer(text):
+                m = match.group(2)
+                assert m.startswith("SDL_")
+                yield m
+
+
 typedef_enum_regex = re.compile(r"\[Typedef]\s*public enum (SDL_\w+)", re.MULTILINE)
 
 
@@ -217,6 +232,11 @@ def run_clangsharp(command, header: Header):
         if rsp.is_file():
             cmd.append(f"@{rsp}")
 
+    to_exclude = list(get_manually_written_symbols(header))
+    if to_exclude:
+        cmd.append("--exclude")
+        cmd.extend(to_exclude)
+
     subprocess.run(cmd)
     return header.output_file()