diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.cpp b/src/gallium/drivers/radeonsi/si_state_shaders.cpp
index 32e0c33febc..f3572c9c3b2 100644
--- a/src/gallium/drivers/radeonsi/si_state_shaders.cpp
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.cpp
@@ -46,6 +46,11 @@ unsigned si_determine_wave_size(struct si_screen *sscreen, struct si_shader *sha
        (stage == MESA_SHADER_GEOMETRY && !shader->key.ge.as_ngg))
       return 64;
 
+   /* For KHR_shader_subgroup which require a constant subgroup size known by user. */
+   if (info->base.subgroup_size == SUBGROUP_SIZE_API_CONSTANT ||
+       (prev_sel && prev_sel->info.base.subgroup_size == SUBGROUP_SIZE_API_CONSTANT))
+      return 64;
+
    /* Workgroup sizes that are not divisible by 64 use Wave32. */
    if (stage == MESA_SHADER_COMPUTE && !info->base.workgroup_size_variable &&
        (info->base.workgroup_size[0] *