diff --git a/servers/rendering/renderer_rd/shaders/forward_mobile/scene_forward_mobile.glsl b/servers/rendering/renderer_rd/shaders/forward_mobile/scene_forward_mobile.glsl
index fa64adf6bf..1b6e53e670 100644
--- a/servers/rendering/renderer_rd/shaders/forward_mobile/scene_forward_mobile.glsl
+++ b/servers/rendering/renderer_rd/shaders/forward_mobile/scene_forward_mobile.glsl
@@ -1666,7 +1666,7 @@ void main() {
 		float lod;
 		half blend = half(modf(roughness_lod, lod));
 
-		float ref_lod = vec3_to_oct_lod(dFdx(cc_radiance_ref_vec), dFdy(cc_radiance_ref_vec), scene_data_block.data.radiance_pixel_size);
+		float ref_lod = vec3_to_oct_lod(dFdx(vec3(cc_radiance_ref_vec)), dFdy(vec3(cc_radiance_ref_vec)), scene_data_block.data.radiance_pixel_size);
 		vec2 ref_uv = vec3_to_oct_with_border(cc_radiance_ref_vec, vec2(scene_data_block.data.radiance_border_size, 1.0 - scene_data_block.data.radiance_border_size * 2.0));
 		hvec3 clearcoat_sample_a = hvec3(textureLod(sampler2DArray(radiance_octmap, DEFAULT_SAMPLER_LINEAR_WITH_MIPMAPS_CLAMP), vec3(ref_uv, lod), ref_lod).rgb);
 		hvec3 clearcoat_sample_b = hvec3(textureLod(sampler2DArray(radiance_octmap, DEFAULT_SAMPLER_LINEAR_WITH_MIPMAPS_CLAMP), vec3(ref_uv, lod + 1), ref_lod).rgb);