diff --git a/src/amd/compiler/aco_live_var_analysis.cpp b/src/amd/compiler/aco_live_var_analysis.cpp
index 0ecc9575f20..bedc829a901 100644
--- a/src/amd/compiler/aco_live_var_analysis.cpp
+++ b/src/amd/compiler/aco_live_var_analysis.cpp
@@ -309,8 +309,12 @@ calc_waves_per_workgroup(Program* program)
 uint16_t
 get_extra_sgprs(Program* program)
 {
-   /* We don't use this register on GFX6-8 and it's removed on GFX10+. */
-   bool needs_flat_scr = program->config->scratch_bytes_per_wave && program->gfx_level == GFX9;
+   /* We don't use this register on GFX6-8 and it's removed on GFX10+. RT uses scratch but we don't
+    * yet know how much.
+    */
+   bool needs_flat_scr =
+      (program->config->scratch_bytes_per_wave || program->stage == raytracing_cs) &&
+      program->gfx_level == GFX9;
 
    if (program->gfx_level >= GFX10) {
       assert(!program->dev.xnack_enabled);