diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c
index d68ac324d07..f737f8b3b53 100644
--- a/src/intel/isl/isl.c
+++ b/src/intel/isl/isl.c
@@ -2020,6 +2020,16 @@ isl_surf_get_ccs_surf(const struct isl_device *dev,
       if (surf->tiling != ISL_TILING_Y0)
          return false;
 
+      /* BSpec 44930:
+       *
+       *    Linear CCS is only allowed for Untyped Buffers but only via HDC
+       *    Data-Port messages.
+       *
+       * We probably want to limit linear CCS to storage usage and check that
+       * the shaders actually use only untyped messages.
+       */
+      assert(surf->tiling != ISL_TILING_LINEAR);
+
       switch (isl_format_get_layout(surf->format)->bpb) {
       case 8:     ccs_format = ISL_FORMAT_GEN12_CCS_8BPP_Y0;    break;
       case 16:    ccs_format = ISL_FORMAT_GEN12_CCS_16BPP_Y0;   break;