diff --git a/src/core/hle/D3D8/Direct3D9/FixedFunctionPixelShader.hlsl b/src/core/hle/D3D8/Direct3D9/FixedFunctionPixelShader.hlsl
index 9f8784faf..bc676711a 100644
--- a/src/core/hle/D3D8/Direct3D9/FixedFunctionPixelShader.hlsl
+++ b/src/core/hle/D3D8/Direct3D9/FixedFunctionPixelShader.hlsl
@@ -74,13 +74,7 @@ float4 ExecuteTextureOp(float op, float4 arg1, float4 arg2, float4 arg0, Texture
 
 	// Note if we use ifs here instead of else if
 	// D3DCompile may stackoverflow at runtime
-
-	// X_D3DTOP_DISABLE can only be reached by ALPHAOP
-	// It's documented as undefined behaviour
-	// Test case: DoA:Xtreme menu, GTA III logos
-	if (op == X_D3DTOP_DISABLE)
-		return 1;
-	else if (op == X_D3DTOP_SELECTARG1)
+	if (op == X_D3DTOP_SELECTARG1)
 		return arg1;
 	else if (op == X_D3DTOP_SELECTARG2)
 		return arg2;
@@ -213,9 +207,14 @@ TextureArgs ExecuteTextureStage(
 	float4 aArg0 = GetArg(s.ALPHAARG0, ctx);
 
 	// Execute texture operation
-	float4 value;
+	// ALPHAOP == X_D3DTOP_DISABLE is undefined behaviour
+	// Using an intermediate value matches known cases...
+	// Test case: DoA:Xtreme (menu water), GTA III (logos), Crash Wrath of Cortex (relics UI)
+	static float4 value = 1;
 	value.rgb = ExecuteTextureOp(s.COLOROP, cArg1, cArg2, cArg0, ctx, stage).rgb;
-	value.a = ExecuteTextureOp(s.ALPHAOP, aArg1, aArg2, aArg0, ctx, stage).a;
+	if (s.ALPHAOP != X_D3DTOP_DISABLE) {
+		value.a = ExecuteTextureOp(s.ALPHAOP, aArg1, aArg2, aArg0, ctx, stage).a;
+	}
 
 	// Save the result
 	// Note RESULTARG should either be CURRENT or TEMP
diff --git a/src/core/hle/D3D8/XbPixelShader.cpp b/src/core/hle/D3D8/XbPixelShader.cpp
index 6b8364764..204c1f8ca 100644
--- a/src/core/hle/D3D8/XbPixelShader.cpp
+++ b/src/core/hle/D3D8/XbPixelShader.cpp
@@ -818,7 +818,10 @@ IDirect3DPixelShader9* GetFixedFunctionShader()
 		states[i].COLORARG1 = (float)XboxTextureStates.Get(i, xbox::X_D3DTSS_COLORARG1);
 		states[i].COLORARG2 = (float)XboxTextureStates.Get(i, xbox::X_D3DTSS_COLORARG2);
 
-		states[i].ALPHAOP = (float)XboxTextureStates.Get(i, xbox::X_D3DTSS_ALPHAOP);
+		auto alphaOp = XboxTextureStates.Get(i, xbox::X_D3DTSS_ALPHAOP);
+		if (alphaOp == X_D3DTOP_DISABLE) LOG_TEST_CASE("Alpha stage disabled when colour stage is enabled");
+
+		states[i].ALPHAOP = (float)alphaOp;
 		states[i].ALPHAARG0 = (float)XboxTextureStates.Get(i, xbox::X_D3DTSS_ALPHAARG0);
 		states[i].ALPHAARG1 = (float)XboxTextureStates.Get(i, xbox::X_D3DTSS_ALPHAARG1);
 		states[i].ALPHAARG2 = (float)XboxTextureStates.Get(i, xbox::X_D3DTSS_ALPHAARG2);
@@ -879,18 +882,15 @@ IDirect3DPixelShader9* GetFixedFunctionShader()
 		auto s = states[i];
 		stageSetup << target << "COLOROP = " << GetD3DTOPString(s.COLOROP) << ";\n";
 
-		// TODO handle texture arg flags
 		stageSetup << target << "COLORARG0 = " << GetD3DTASumString(s.COLORARG0) << ";\n";
 		stageSetup << target << "COLORARG1 = " << GetD3DTASumString(s.COLORARG1) << ";\n";
 		stageSetup << target << "COLORARG2 = " << GetD3DTASumString(s.COLORARG2) << ";\n";
 
 		stageSetup << target << "ALPHAOP = " << GetD3DTOPString(s.ALPHAOP) << ";\n";
 
-		if (states[i].ALPHAOP != X_D3DTOP_DISABLE) {
-			stageSetup << target << "ALPHAARG0 = " << GetD3DTASumString(s.ALPHAARG0) << ";\n";
-			stageSetup << target << "ALPHAARG1 = " << GetD3DTASumString(s.ALPHAARG1) << ";\n";
-			stageSetup << target << "ALPHAARG2 = " << GetD3DTASumString(s.ALPHAARG2) << ";\n";
-		}
+		stageSetup << target << "ALPHAARG0 = " << GetD3DTASumString(s.ALPHAARG0) << ";\n";
+		stageSetup << target << "ALPHAARG1 = " << GetD3DTASumString(s.ALPHAARG1) << ";\n";
+		stageSetup << target << "ALPHAARG2 = " << GetD3DTASumString(s.ALPHAARG2) << ";\n";
 
 		stageSetup << target << "RESULTARG = " << GetD3DTASumString(s.RESULTARG, false) << ";\n";
 		stageSetup << '\n';