diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
index 1fe141a3..2d2e904b 100644
--- a/libs/vkd3d-shader/hlsl_codegen.c
+++ b/libs/vkd3d-shader/hlsl_codegen.c
@@ -4123,13 +4123,46 @@ static void allocate_const_registers(struct hlsl_ctx *ctx, struct hlsl_ir_functi
 
     LIST_FOR_EACH_ENTRY(var, &ctx->extern_vars, struct hlsl_ir_var, extern_entry)
     {
-        if (var->is_uniform && var->last_read)
+        unsigned int reg_size = var->data_type->reg_size[HLSL_REGSET_NUMERIC];
+
+        if (!var->is_uniform || !var->last_read || reg_size == 0)
+            continue;
+
+        if (var->reg_reservation.reg_type == 'c')
         {
-            unsigned int reg_size = var->data_type->reg_size[HLSL_REGSET_NUMERIC];
+            unsigned int reg_idx = var->reg_reservation.reg_index;
+            unsigned int i;
 
-            if (reg_size == 0)
-                continue;
+            assert(reg_size % 4 == 0);
+            for (i = 0; i < reg_size / 4; ++i)
+            {
+                if (get_available_writemask(&allocator, 1, UINT_MAX, reg_idx + i) != VKD3DSP_WRITEMASK_ALL)
+                {
+                    hlsl_error(ctx, &var->loc, VKD3D_SHADER_ERROR_HLSL_INVALID_RESERVATION,
+                            "Overlapping register() reservations on 'c%u'.", reg_idx + i);
+                }
 
+                record_allocation(ctx, &allocator, reg_idx + i, VKD3DSP_WRITEMASK_ALL, 1, UINT_MAX);
+            }
+
+            var->regs[HLSL_REGSET_NUMERIC].id = reg_idx;
+            var->regs[HLSL_REGSET_NUMERIC].allocation_size = reg_size / 4;
+            var->regs[HLSL_REGSET_NUMERIC].writemask = VKD3DSP_WRITEMASK_ALL;
+            var->regs[HLSL_REGSET_NUMERIC].allocated = true;
+            TRACE("Allocated reserved %s to %s.\n", var->name,
+                    debug_register('c', var->regs[HLSL_REGSET_NUMERIC], var->data_type));
+        }
+    }
+
+    LIST_FOR_EACH_ENTRY(var, &ctx->extern_vars, struct hlsl_ir_var, extern_entry)
+    {
+        unsigned int reg_size = var->data_type->reg_size[HLSL_REGSET_NUMERIC];
+
+        if (!var->is_uniform || !var->last_read || reg_size == 0)
+            continue;
+
+        if (!var->regs[HLSL_REGSET_NUMERIC].allocated)
+        {
             var->regs[HLSL_REGSET_NUMERIC] = allocate_numeric_registers_for_type(ctx, &allocator,
                     1, UINT_MAX, var->data_type);
             TRACE("Allocated %s to %s.\n", var->name,
diff --git a/tests/hlsl/register-reservations-numeric.shader_test b/tests/hlsl/register-reservations-numeric.shader_test
index f89cb139..9b2bae57 100644
--- a/tests/hlsl/register-reservations-numeric.shader_test
+++ b/tests/hlsl/register-reservations-numeric.shader_test
@@ -1,4 +1,4 @@
-[pixel shader fail(sm<6) todo]
+[pixel shader fail(sm<6) todo(sm>=4)]
 // Overlapping register(cX) reservations are not allowed except on SM6, where they are aliased.
 // On SM1 this gives hr 0x88760b59.
 float a : register(c0);
@@ -24,7 +24,7 @@ float4 main() : sv_target
 uniform 0 float4 0.1 0.2 0.3 0.4
 uniform 4 float4 1.1 1.2 1.3 1.4
 draw quad
-todo(sm<6) probe all rgba (1.1, 1.4, 0.2, 0.3)
+todo(sm>=4 & sm<6) probe all rgba (1.1, 1.4, 0.2, 0.3)
 
 
 [pixel shader]
@@ -43,7 +43,7 @@ uniform 8 float4 2.1 2.2 2.3 2.4
 uniform 12 float4 3.1 3.2 3.3 3.4
 uniform 16 float4 4.1 4.2 4.3 4.4
 draw quad
-todo(sm<6) probe all rgba (4.1, 4.2, 1.3, 1.4)
+todo(sm>=4 & sm<6) probe all rgba (4.1, 4.2, 1.3, 1.4)
 
 
 [require]
@@ -64,7 +64,7 @@ uniform 4 float4 1.1 1.2 1.3 1.4
 uniform 8 float4 2.1 2.2 2.3 2.4
 uniform 12 float4 3.1 3.2 3.3 3.4
 draw quad
-todo probe all rgba (2.1, 0.1, 0.0, 0.0)
+probe all rgba (2.1, 0.1, 0.0, 0.0)
 
 
 [require]
@@ -132,7 +132,7 @@ uniform 4 float4 1.1 1.2 1.3 1.4
 uniform 8 float4 2.1 2.2 2.3 2.4
 uniform 12 float4 3.1 3.2 3.3 3.4
 draw quad
-todo probe all rgba (2.1, 2.2, 3.1, 0.0)
+probe all rgba (2.1, 2.2, 3.1, 0.0)
 
 
 [require]