diff --git a/ref_vk/shaders/ray_light_direct.comp b/ref_vk/shaders/ray_light_direct.comp
index cc870057..2f822942 100644
--- a/ref_vk/shaders/ray_light_direct.comp
+++ b/ref_vk/shaders/ray_light_direct.comp
@@ -5,7 +5,7 @@
 
 #include "utils.glsl"
 
-layout(local_size_x = 16, local_size_y = 8, local_size_z = 1) in;
+layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;
 
 #include "ray_light_direct_iface.h"
 
diff --git a/ref_vk/vk_ray_light_direct.c b/ref_vk/vk_ray_light_direct.c
index aa64e800..5780fddf 100644
--- a/ref_vk/vk_ray_light_direct.c
+++ b/ref_vk/vk_ray_light_direct.c
@@ -164,7 +164,7 @@ void XVK_RayTraceLightDirectReloadPipeline( void ) {
 }
 
 void XVK_RayTraceLightDirect( VkCommandBuffer cmdbuf, const xvk_ray_trace_light_direct_t *args ) {
-	const uint32_t WG_W = 16;
+	const uint32_t WG_W = 8;
 	const uint32_t WG_H = 8;
 
 	updateDescriptors( args );