diff --git a/app/src/main/java/chess/render/shader/BoardShader.java b/app/src/main/java/chess/render/shader/BoardShader.java
index 15c6c10..345bb5b 100644
--- a/app/src/main/java/chess/render/shader/BoardShader.java
+++ b/app/src/main/java/chess/render/shader/BoardShader.java
@@ -12,7 +12,7 @@ public class BoardShader extends ShaderProgram {
 
 			uniform mat4 camMatrix;
 
-			out vec3 pass_color;
+			flat out vec3 pass_color;
 
 			void main(void){
 				gl_Position = camMatrix * vec4(position, 1.0);
@@ -23,7 +23,7 @@ public class BoardShader extends ShaderProgram {
 	private static String fragmentShader = """
 			#version 330
 
-			in vec3 pass_color;
+			flat in vec3 pass_color;
 
 			out vec4 out_color;