diff --git a/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs b/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs
index 07d33d1..d81360f 100644
--- a/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs
+++ b/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs
@@ -80,7 +80,13 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
     private int _transparentByteOffset;
 #pragma warning restore CS0169
 
-    [StructLayout(LayoutKind.Sequential, Pack = 4)]
+    // std430 layout: ulong TextureHandle (uvec2) at offset 0, uint TextureLayer
+    // at offset 8, uint Flags at offset 12. Total 16 bytes.
+    // Pack=8 (not 4) because std430's uvec2 requires 8-byte alignment — Pack=4
+    // works today by accident (TextureHandle is the first field, so offset 0 is
+    // always 8-byte aligned), but adding a 4-byte field before TextureHandle
+    // without bumping Pack would silently misalign the GPU struct.
+    [StructLayout(LayoutKind.Sequential, Pack = 8)]
     private struct BatchData
     {
         public ulong TextureHandle;   // bindless handle (uvec2 in GLSL)