diff --git a/libs/vkd3d-shader/hlsl.y b/libs/vkd3d-shader/hlsl.y
index a40683d6..b247c791 100644
--- a/libs/vkd3d-shader/hlsl.y
+++ b/libs/vkd3d-shader/hlsl.y
@@ -3026,7 +3026,7 @@ static struct hlsl_ir_function_decl *find_function_call(struct hlsl_ctx *ctx,
         {
             if (compatible_match)
             {
-                hlsl_fixme(ctx, loc, "Prioritize between multiple compatible function overloads.");
+                hlsl_error(ctx, loc, VKD3D_SHADER_ERROR_HLSL_AMBIGUOUS_CALL, "Ambiguous function call.");
                 break;
             }
             compatible_match = decl;
diff --git a/libs/vkd3d-shader/vkd3d_shader_private.h b/libs/vkd3d-shader/vkd3d_shader_private.h
index 09e0e66c..f451e693 100644
--- a/libs/vkd3d-shader/vkd3d_shader_private.h
+++ b/libs/vkd3d-shader/vkd3d_shader_private.h
@@ -163,6 +163,7 @@ enum vkd3d_shader_error
     VKD3D_SHADER_ERROR_HLSL_INVALID_OUTPUT_PRIMITIVE    = 5037,
     VKD3D_SHADER_ERROR_HLSL_INVALID_PARTITIONING        = 5038,
     VKD3D_SHADER_ERROR_HLSL_MISPLACED_SAMPLER_STATE     = 5039,
+    VKD3D_SHADER_ERROR_HLSL_AMBIGUOUS_CALL              = 5040,
 
     VKD3D_SHADER_WARNING_HLSL_IMPLICIT_TRUNCATION       = 5300,
     VKD3D_SHADER_WARNING_HLSL_DIVISION_BY_ZERO          = 5301,
diff --git a/tests/hlsl/function-overload.shader_test b/tests/hlsl/function-overload.shader_test
index 5fc1d1f9..6f666f4a 100644
--- a/tests/hlsl/function-overload.shader_test
+++ b/tests/hlsl/function-overload.shader_test
@@ -41,7 +41,7 @@ todo(sm<6) draw quad
 probe (0, 0) rgba (0.1, 0.2, 0.1, 0.2)
 
 
-[pixel shader fail todo]
+[pixel shader fail]
 float func(int arg)
 {
     return 1.0;
@@ -96,7 +96,7 @@ float4 main() : sv_target
 
 % ...but invoking them is considered ambiguous and fails.
 
-[pixel shader fail todo]
+[pixel shader fail]
 
 void func(float arg) {}
 void func(float1 arg) {}
@@ -108,7 +108,7 @@ float4 main() : sv_target
     return 1.0;
 }
 
-[pixel shader fail todo]
+[pixel shader fail]
 
 void func(float arg) {}
 void func(float1 arg) {}
@@ -123,7 +123,7 @@ float4 main() : sv_target
 
 % This holds true even if one variant isn't actually defined.
 
-[pixel shader fail todo]
+[pixel shader fail]
 
 void func(float arg);
 void func(float1 arg) {}
@@ -136,7 +136,7 @@ float4 main() : sv_target
 }
 
 % Narrows have the same priority, regardless of how much narrowing is done.
-[pixel shader fail todo]
+[pixel shader fail]
 
 float4 func(float3 x)
 {
@@ -154,7 +154,7 @@ float4 main() : sv_target
 }
 
 % Even if one axis has less narrowing.
-[pixel shader fail todo]
+[pixel shader fail]
 
 float4 func(float4x3 x)
 {
@@ -348,7 +348,7 @@ todo(sm<6) probe (0, 0) rgba(2.0, 2.0, 2.0, 2.0)
 
 % Some matrices are implicitly compatible with vectors and will ambiguate with them.
 
-[pixel shader fail todo]
+[pixel shader fail]
 
 float4 func(float2x2 x)
 {
@@ -365,7 +365,7 @@ float4 main() : sv_target
     return func(float4(0, 0, 0, 0));
 }
 
-[pixel shader fail todo]
+[pixel shader fail]
 
 float4 func(float1x3 x)
 {
@@ -384,7 +384,7 @@ float4 main() : sv_target
 
 % Structs are evaluated on a per-component basis.
 
-[pixel shader fail todo]
+[pixel shader fail]
 struct a
 {
     float4 a;
@@ -421,7 +421,7 @@ float4 main() : sv_target
 
 % Arrays are evaluated on a per component basis.
 
-[pixel shader fail todo]
+[pixel shader fail]
 
 float4 func(float4 x[1])
 {