diff --git a/libs/vkd3d-shader/tpf.c b/libs/vkd3d-shader/tpf.c
index c6108641..8bb9ec24 100644
--- a/libs/vkd3d-shader/tpf.c
+++ b/libs/vkd3d-shader/tpf.c
@@ -2814,6 +2814,7 @@ bool sysval_semantic_from_hlsl(enum vkd3d_shader_sysval_semantic *semantic,
         {"sv_isfrontface",              false, VKD3D_SHADER_TYPE_PIXEL,     VKD3D_SHADER_SV_IS_FRONT_FACE},
         {"sv_rendertargetarrayindex",   false, VKD3D_SHADER_TYPE_PIXEL,     VKD3D_SHADER_SV_RENDER_TARGET_ARRAY_INDEX},
         {"sv_viewportarrayindex",       false, VKD3D_SHADER_TYPE_PIXEL,     VKD3D_SHADER_SV_VIEWPORT_ARRAY_INDEX},
+        {"sv_sampleindex",              false, VKD3D_SHADER_TYPE_PIXEL,     VKD3D_SHADER_SV_SAMPLE_INDEX},
 
         {"color",                       true,  VKD3D_SHADER_TYPE_PIXEL,     VKD3D_SHADER_SV_TARGET},
         {"depth",                       true,  VKD3D_SHADER_TYPE_PIXEL,     VKD3D_SHADER_SV_DEPTH},
@@ -4461,6 +4462,7 @@ static void write_sm4_dcl_semantic(const struct tpf_writer *tpf, const struct hl
             case VKD3D_SHADER_SV_INSTANCE_ID:
             case VKD3D_SHADER_SV_PRIMITIVE_ID:
             case VKD3D_SHADER_SV_VERTEX_ID:
+            case VKD3D_SHADER_SV_SAMPLE_INDEX:
                 instr.opcode = (profile->type == VKD3D_SHADER_TYPE_PIXEL)
                         ? VKD3D_SM4_OP_DCL_INPUT_PS_SGV : VKD3D_SM4_OP_DCL_INPUT_SGV;
                 break;
diff --git a/tests/hlsl_d3d12.c b/tests/hlsl_d3d12.c
index 43b1f0e9..a655e467 100644
--- a/tests/hlsl_d3d12.c
+++ b/tests/hlsl_d3d12.c
@@ -2062,7 +2062,8 @@ static void test_signature_reflection(void)
         "        out uint c : sv_coverage,\n"
         "        in float4 d : position,\n"
         "        in float4 e : sv_position,\n"
-        "        out float f : sv_depth)\n"
+        "        out float f : sv_depth,\n"
+        "        in uint g : sv_sampleindex)\n"
         "{\n"
         "    b = d;\n"
         "    c = 0;\n"
@@ -2071,9 +2072,10 @@ static void test_signature_reflection(void)
 
     static const D3D12_SIGNATURE_PARAMETER_DESC ps1_inputs[] =
     {
-        {"apple",       0, 0, D3D_NAME_UNDEFINED, D3D_REGISTER_COMPONENT_FLOAT32, 0x3},
-        {"position",    0, 1, D3D_NAME_UNDEFINED, D3D_REGISTER_COMPONENT_FLOAT32, 0xf, 0xf},
-        {"sv_position", 0, 2, D3D_NAME_POSITION,  D3D_REGISTER_COMPONENT_FLOAT32, 0xf},
+        {"apple",          0, 0, D3D_NAME_UNDEFINED,     D3D_REGISTER_COMPONENT_FLOAT32, 0x3},
+        {"position",       0, 1, D3D_NAME_UNDEFINED,     D3D_REGISTER_COMPONENT_FLOAT32, 0xf, 0xf},
+        {"sv_position",    0, 2, D3D_NAME_POSITION,      D3D_REGISTER_COMPONENT_FLOAT32, 0xf},
+        {"sv_sampleindex", 0, 3, D3D_NAME_SAMPLE_INDEX,  D3D_REGISTER_COMPONENT_UINT32,  0x1},
     };
 
     static const D3D12_SIGNATURE_PARAMETER_DESC ps1_outputs[] =