diff --git a/resources/shaders/110/phong.fs b/resources/shaders/110/phong.fs
index a47a24fdea..7d1e7bfe8c 100644
--- a/resources/shaders/110/phong.fs
+++ b/resources/shaders/110/phong.fs
@@ -41,6 +41,7 @@ struct SlopeDetection
     bool actived;
     float normal_z;
     mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };
 
 uniform vec4 uniform_color;
diff --git a/resources/shaders/140/phong.fs b/resources/shaders/140/phong.fs
index 809621b76d..4cfae1e03e 100644
--- a/resources/shaders/140/phong.fs
+++ b/resources/shaders/140/phong.fs
@@ -44,6 +44,7 @@ struct SlopeDetection
     bool actived;
     float normal_z;
     mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };
 
 uniform vec4 uniform_color;