diff --git a/GPU/GLES/FragmentShaderGenerator.cpp b/GPU/GLES/FragmentShaderGenerator.cpp
index 793c3f58b2..c0138870e5 100644
--- a/GPU/GLES/FragmentShaderGenerator.cpp
+++ b/GPU/GLES/FragmentShaderGenerator.cpp
@@ -400,6 +400,7 @@ void ComputeFragmentShaderID(FragmentShaderID *id) {
 		bool enableColorDoubling = gstate.isColorDoublingEnabled() && gstate.isTextureMapEnabled();
 		bool doTextureProjection = gstate.getUVGenMode() == GE_TEXMAP_TEXTURE_MATRIX;
 		bool doTextureAlpha = gstate.isTextureAlphaUsed();
+		bool doFlatShading = gstate.getShadeMode() == GE_SHADE_FLAT;
 		ReplaceBlendType replaceBlend = ReplaceBlendWithShader();
 		ReplaceAlphaType stencilToAlpha = ReplaceAlphaWithStencil(replaceBlend);
 
@@ -466,6 +467,7 @@ void ComputeFragmentShaderID(FragmentShaderID *id) {
 			id1 |= gstate.getBlendFuncA() << 6;
 			id1 |= gstate.getBlendFuncB() << 10;
 		}
+		id1 |= (doFlatShading & 1) << 14;
 	}
 
 	id->d[0] = id0;
@@ -575,6 +577,8 @@ void GenerateFragmentShader(char *buffer) {
 	ReplaceBlendType replaceBlend = ReplaceBlendWithShader();
 	ReplaceAlphaType stencilToAlpha = ReplaceAlphaWithStencil(replaceBlend);
 
+	char *shading = gstate.getShadeMode() == GE_SHADE_FLAT ? "flat" : "smooth";
+
 	if (gstate_c.textureFullAlpha && gstate.getTextureFunction() != GE_TEXFUNC_REPLACE)
 		doTextureAlpha = false;
 
@@ -617,9 +621,9 @@ void GenerateFragmentShader(char *buffer) {
 	if (gstate.isTextureMapEnabled() && gstate.getTextureFunction() == GE_TEXFUNC_BLEND)
 		WRITE(p, "uniform vec3 u_texenv;\n");
 
-	WRITE(p, "%s vec4 v_color0;\n", varying);
+	WRITE(p, "%s %s vec4 v_color0;\n", shading, varying);
 	if (lmode)
-		WRITE(p, "%s vec3 v_color1;\n", varying);
+		WRITE(p, "%s %s vec3 v_color1;\n", shading, varying);
 	if (enableFog) {
 		WRITE(p, "uniform vec3 u_fogcolor;\n");
 		WRITE(p, "%s %s float v_fogdepth;\n", varying, highpFog ? "highp" : "mediump");
diff --git a/GPU/GLES/VertexShaderGenerator.cpp b/GPU/GLES/VertexShaderGenerator.cpp
index 4a02c2262d..7f80f3923a 100644
--- a/GPU/GLES/VertexShaderGenerator.cpp
+++ b/GPU/GLES/VertexShaderGenerator.cpp
@@ -52,6 +52,7 @@ void ComputeVertexShaderID(VertexShaderID *id, u32 vertType, int prim, bool useH
 	bool doTexture = gstate.isTextureMapEnabled() && !gstate.isModeClear();
 	bool doTextureProjection = gstate.getUVGenMode() == GE_TEXMAP_TEXTURE_MATRIX;
 	bool doShadeMapping = gstate.getUVGenMode() == GE_TEXMAP_ENVIRONMENT_MAP;
+	bool doFlatShading = gstate.getShadeMode() == GE_SHADE_FLAT;
 
 	bool hasColor = (vertType & GE_VTYPE_COL_MASK) != 0;
 	bool hasNormal = (vertType & GE_VTYPE_NRM_MASK) != 0;
@@ -115,6 +116,7 @@ void ComputeVertexShaderID(VertexShaderID *id, u32 vertType, int prim, bool useH
 			id1 |= (hasTexcoord & 1) << 28;
 		}
 	}
+	id1 |= (doFlatShading & 1) << 29;
 
 	id->d[0] = id0;
 	id->d[1] = id1;
@@ -222,6 +224,8 @@ void GenerateVertexShader(int prim, u32 vertType, char *buffer, bool useHWTransf
 	bool flipV = gstate_c.flipTexture;  // This also means that we are texturing from a render target
 	bool flipNormal = gstate.areNormalsReversed();
 
+	char *shading = gstate.getShadeMode() == GE_SHADE_FLAT ? "flat" : "smooth";
+
 	DoLightComputation doLight[4] = {LIGHT_OFF, LIGHT_OFF, LIGHT_OFF, LIGHT_OFF};
 	if (useHWTransform) {
 		int shadeLight0 = doShadeMapping ? gstate.getUVLS0() : -1;
@@ -326,9 +330,9 @@ void GenerateVertexShader(int prim, u32 vertType, char *buffer, bool useHWTransf
 		WRITE(p, "uniform highp vec2 u_fogcoef;\n");
 	}
 
-	WRITE(p, "%s lowp vec4 v_color0;\n", varying);
+	WRITE(p, "%s %s lowp vec4 v_color0;\n", shading, varying);
 	if (lmode) {
-		WRITE(p, "%s lowp vec3 v_color1;\n", varying);
+		WRITE(p, "%s %s lowp vec3 v_color1;\n", shading, varying);
 	}
 	if (doTexture) {
 		if (doTextureProjection)