diff --git a/src/core/hle/D3D8/Direct3D9/CxbxVertexShaderTemplate.hlsl b/src/core/hle/D3D8/Direct3D9/CxbxVertexShaderTemplate.hlsl
index 19173ae0a..b352be68f 100644
--- a/src/core/hle/D3D8/Direct3D9/CxbxVertexShaderTemplate.hlsl
+++ b/src/core/hle/D3D8/Direct3D9/CxbxVertexShaderTemplate.hlsl
@@ -28,9 +28,9 @@ struct VS_OUTPUT
 // Xbox constant registers
 uniform float4 C[X_D3DVS_CONSTREG_COUNT] : register(c0);
 
-// Vertex input overrides for SetVertexData4f support
-uniform float4 vOverrideValue[16]  : register(c192);
-uniform float4 vOverridePacked[4]  : register(c208);
+// Default values for vertex registers, and whether to use them
+uniform float4 vRegisterDefaultValues[16]  : register(c192);
+uniform float4 vRegisterDefaultFlagsPacked[4]  : register(c208);
 
 uniform float4 xboxViewportScale   : register(c212);
 uniform float4 xboxViewportOffset  : register(c213);
@@ -284,12 +284,12 @@ VS_OUTPUT main(const VS_INPUT xIn)
 	// Input registers
 	float4 v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15;
 
-	// View 4 packed overrides as an array of 16 floats
-	float vOverride[16] = (float[16])vOverridePacked;
+	// Unpack 16 flags from 4 float4 constant registers
+	float vRegisterDefaultFlags[16] = (float[16])vRegisterDefaultFlagsPacked;
 
-	// Initialize input registers from the vertex buffer
-	// Or use an override value set with SetVertexData4f
-	#define init_v(i) v##i = lerp(xIn.v[i], vOverride[i], vOverrideValue[i]);
+	// Initialize input registers from the vertex buffer data
+	// Or use the register's default value (which can be changed by the title)
+	#define init_v(i) v##i = lerp(xIn.v[i], vRegisterDefaultValues[i], vRegisterDefaultFlags[i]);
 	// Note : unroll manually instead of for-loop, because of the ## concatenation
 	init_v( 0); init_v( 1); init_v( 2); init_v( 3);
 	init_v( 4); init_v( 5); init_v( 6); init_v( 7);
diff --git a/src/core/hle/D3D8/Direct3D9/Direct3D9.cpp b/src/core/hle/D3D8/Direct3D9/Direct3D9.cpp
index 337d97661..505de4aba 100644
--- a/src/core/hle/D3D8/Direct3D9/Direct3D9.cpp
+++ b/src/core/hle/D3D8/Direct3D9/Direct3D9.cpp
@@ -547,13 +547,16 @@ const char *CxbxGetErrorDescription(HRESULT hResult)
 }
 
 // TODO move to shader file. Needs to be called whenever a shader or declaration is set
-void SetOverrideFlags(CxbxVertexShader* pCxbxVertexShader) {
+void SetVertexRegisterDefaultFlags(CxbxVertexShader* pCxbxVertexShader) {
 	if (pCxbxVertexShader != nullptr && pCxbxVertexShader->pHostVertexShader != nullptr) {
-		float overrideFlags[16];
+		// Titles can specify default values for registers via calls like SetVertexData4f
+		// HLSL shaders need to know whether to use vertex data or default vertex shader values
+		// Any register not in the vertex declaration should be set to the default value
+		float vertexDefaultFlags[16];
 		for (int i = 0; i < 16; i++) {
-			overrideFlags[i] = pCxbxVertexShader->VertexShaderInfo.vRegisterInDeclaration[i] ? 1.0f : 0.0f;
+			vertexDefaultFlags[i] = pCxbxVertexShader->VertexShaderInfo.vRegisterInDeclaration[i] ? 0.0f : 1.0f;
 		}
-		g_pD3DDevice->SetVertexShaderConstantF(CXBX_D3DVS_CONSTREG_VERTEXDATA4F_FLAG_BASE, overrideFlags, 4);
+		g_pD3DDevice->SetVertexShaderConstantF(CXBX_D3DVS_CONSTREG_VREGDEFAULTS_FLAG_BASE, vertexDefaultFlags, 4);
 	}
 }
 
@@ -3580,7 +3583,7 @@ VOID WINAPI XTL::EMUPATCH(D3DDevice_SelectVertexShader)
 		pHostVertexShader = pCxbxVertexShader->pHostVertexShader;
 		HostFVF = pCxbxVertexShader->HostFVF;
 
-		SetOverrideFlags(pCxbxVertexShader);
+		SetVertexRegisterDefaultFlags(pCxbxVertexShader);
 	}
 
 	hRet = g_pD3DDevice->SetVertexDeclaration(pHostVertexDeclaration);
@@ -4758,7 +4761,7 @@ VOID WINAPI XTL::EMUPATCH(D3DDevice_SetVertexData4f)
 		FLOAT values[] = {a,b,c,d};
 		if (Register < 0) LOG_TEST_CASE("Register < 0");
 		if (Register >= 16) LOG_TEST_CASE("Register >= 16");
-		g_pD3DDevice->SetVertexShaderConstantF(CXBX_D3DVS_CONSTREG_VERTEXDATA4F_BASE + Register, values, 1);
+		g_pD3DDevice->SetVertexShaderConstantF(CXBX_D3DVS_CONSTREG_VREGDEFAULTS_BASE + Register, values, 1);
 	}
 
 	// Grow g_InlineVertexBuffer_Table to contain at least current, and a potentially next vertex
@@ -6804,7 +6807,7 @@ VOID WINAPI XTL::EMUPATCH(D3DDevice_SetVertexShader)
 		}
 		else
 		{
-			SetOverrideFlags(pCxbxVertexShader);
+			SetVertexRegisterDefaultFlags(pCxbxVertexShader);
 
 			hRet = g_pD3DDevice->SetVertexShader(pCxbxVertexShader->pHostVertexShader);
 			DEBUG_D3DRESULT(hRet, "g_pD3DDevice->SetVertexShader(VshHandleIsVertexShader)");
diff --git a/src/core/hle/D3D8/XbD3D8Types.h b/src/core/hle/D3D8/XbD3D8Types.h
index 974a0b26a..daf566898 100644
--- a/src/core/hle/D3D8/XbD3D8Types.h
+++ b/src/core/hle/D3D8/XbD3D8Types.h
@@ -991,9 +991,9 @@ typedef DWORD X_VERTEXSHADERCONSTANTMODE;
 
 // Special Registers, used to pass additional information to the shaders
 // TODO co-locate shader workaround constants with shader code
-#define CXBX_D3DVS_CONSTREG_VERTEXDATA4F_BASE      (X_D3DVS_CONSTREG_COUNT)
-#define CXBX_D3DVS_CONSTREG_VERTEXDATA4F_FLAG_BASE (CXBX_D3DVS_CONSTREG_VERTEXDATA4F_BASE + 16)
-#define CXBX_D3DVS_VIEWPORT_SCALE_MIRROR           (CXBX_D3DVS_CONSTREG_VERTEXDATA4F_FLAG_BASE + 4)
+#define CXBX_D3DVS_CONSTREG_VREGDEFAULTS_BASE      (X_D3DVS_CONSTREG_COUNT)
+#define CXBX_D3DVS_CONSTREG_VREGDEFAULTS_FLAG_BASE (CXBX_D3DVS_CONSTREG_VREGDEFAULTS_BASE + 16)
+#define CXBX_D3DVS_VIEWPORT_SCALE_MIRROR           (CXBX_D3DVS_CONSTREG_VREGDEFAULTS_FLAG_BASE + 4)
 #define CXBX_D3DVS_VIEWPORT_OFFSET_MIRROR          (CXBX_D3DVS_VIEWPORT_SCALE_MIRROR + 1)
 
 #define X_D3DSCM_RESERVED_CONSTANT_SCALE_CORRECTED (X_D3DSCM_RESERVED_CONSTANT_SCALE + X_D3DSCM_CORRECTION)