diff --git a/src/asahi/lib/agx_nir_lower_tess.c b/src/asahi/lib/agx_nir_lower_tess.c
index 61b23aff285..ba504949ab4 100644
--- a/src/asahi/lib/agx_nir_lower_tess.c
+++ b/src/asahi/lib/agx_nir_lower_tess.c
@@ -31,9 +31,8 @@ tcs_instance_id(nir_builder *b)
 static nir_def *
 tcs_unrolled_id(nir_builder *b)
 {
-   nir_def *stride = nir_channel(b, nir_load_num_workgroups(b), 0);
-
-   return nir_iadd(b, nir_imul(b, tcs_instance_id(b), stride), tcs_patch_id(b));
+   return libagx_tcs_unrolled_id(b, nir_load_tess_param_buffer_agx(b),
+                                 nir_load_workgroup_id(b));
 }
 
 uint64_t
diff --git a/src/asahi/lib/shaders/tessellation.cl b/src/asahi/lib/shaders/tessellation.cl
index 5dfea8345a1..f99a1e34a29 100644
--- a/src/asahi/lib/shaders/tessellation.cl
+++ b/src/asahi/lib/shaders/tessellation.cl
@@ -19,6 +19,12 @@ libagx_tes_patch_vertices_in(constant struct libagx_tess_args *p)
    return p->output_patch_size;
 }
 
+uint
+libagx_tcs_unrolled_id(constant struct libagx_tess_args *p, uint3 wg_id)
+{
+   return (wg_id.y * p->patches_per_instance) + wg_id.x;
+}
+
 ushort
 libagx_tcs_in_offset(uint vtx, gl_varying_slot location,
                      uint64_t crosslane_vs_out_mask)