diff --git a/libs/vkd3d-shader/d3dbc.c b/libs/vkd3d-shader/d3dbc.c
index 24a95224..c7991407 100644
--- a/libs/vkd3d-shader/d3dbc.c
+++ b/libs/vkd3d-shader/d3dbc.c
@@ -1713,7 +1713,7 @@ static void write_sm1_uniforms(struct hlsl_ctx *ctx, struct vkd3d_bytecode_buffe
 
         for (r = 0; r <= HLSL_REGSET_LAST; ++r)
         {
-            if (var->semantic.name || !var->regs[r].allocated)
+            if (var->semantic.name || !var->regs[r].allocated || !var->last_read)
                 continue;
 
             ++uniform_count;
@@ -1751,7 +1751,7 @@ static void write_sm1_uniforms(struct hlsl_ctx *ctx, struct vkd3d_bytecode_buffe
 
         for (r = 0; r <= HLSL_REGSET_LAST; ++r)
         {
-            if (var->semantic.name || !var->regs[r].allocated)
+            if (var->semantic.name || !var->regs[r].allocated || !var->last_read)
                 continue;
 
             put_u32(buffer, 0); /* name */
@@ -1780,7 +1780,7 @@ static void write_sm1_uniforms(struct hlsl_ctx *ctx, struct vkd3d_bytecode_buffe
         {
             size_t var_offset, name_offset;
 
-            if (var->semantic.name || !var->regs[r].allocated)
+            if (var->semantic.name || !var->regs[r].allocated || !var->last_read)
                 continue;
 
             var_offset = vars_start + (uniform_count * 5 * sizeof(uint32_t));
diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
index 8882deaf..4af55293 100644
--- a/libs/vkd3d-shader/hlsl_codegen.c
+++ b/libs/vkd3d-shader/hlsl_codegen.c
@@ -4529,7 +4529,7 @@ static void allocate_const_registers(struct hlsl_ctx *ctx, struct hlsl_ir_functi
     {
         unsigned int reg_size = var->data_type->reg_size[HLSL_REGSET_NUMERIC];
 
-        if (!var->is_uniform || !var->last_read || reg_size == 0)
+        if (!var->is_uniform || reg_size == 0)
             continue;
 
         if (var->reg_reservation.reg_type == 'c')
diff --git a/tests/hlsl/sm1-const-allocation.shader_test b/tests/hlsl/sm1-const-allocation.shader_test
index ca641b14..0a4340ea 100644
--- a/tests/hlsl/sm1-const-allocation.shader_test
+++ b/tests/hlsl/sm1-const-allocation.shader_test
@@ -339,7 +339,7 @@ uniform 16 float 4
 uniform 20 float 5
 uniform 24 float 6
 draw quad
-todo probe all rgba (0, 6, 0, 0)
+probe all rgba (0, 6, 0, 0)
 
 
 [pixel shader]
@@ -372,7 +372,7 @@ uniform 16 float 4
 uniform 20 float 5
 uniform 24 float 6
 draw quad
-todo probe all rgba (6, 1, 0, 0)
+probe all rgba (6, 1, 0, 0)
 
 
 [pixel shader todo]