diff --git a/src/compiler/nir/nir_lower_system_values.c b/src/compiler/nir/nir_lower_system_values.c
index d91366c82d0..5253efd0098 100644
--- a/src/compiler/nir/nir_lower_system_values.c
+++ b/src/compiler/nir/nir_lower_system_values.c
@@ -423,6 +423,24 @@ lower_compute_system_value_filter(const nir_instr *instr, const void *_state)
    return instr->type == nir_instr_type_intrinsic;
 }
 
+static nir_ssa_def *
+try_lower_id_to_index_1d(nir_builder *b, nir_ssa_def *index, const uint16_t *size)
+{
+   /* size_x = 1, size_y = 1, therefore Z = local index */
+   if (size[0] == 1 && size[1] == 1)
+      return nir_vec3(b, nir_imm_int(b, 0), nir_imm_int(b, 0), index);
+
+   /* size_x = 1, size_z = 1, therefore Y = local index */
+   if (size[0] == 1 && size[2] == 1)
+      return nir_vec3(b, nir_imm_int(b, 0), index, nir_imm_int(b, 0));
+
+   /* size_y = 1, size_z = 1, therefore X = local index */
+   if (size[1] == 1 && size[2] == 1)
+      return nir_vec3(b, index, nir_imm_int(b, 0), nir_imm_int(b, 0));
+
+   return NULL;
+}
+
 static nir_ssa_def *
 lower_compute_system_value_instr(nir_builder *b,
                                  nir_instr *instr, void *_state)
@@ -454,20 +472,10 @@ lower_compute_system_value_instr(nir_builder *b,
              * this way we don't leave behind extra ALU instrs.
              */
 
-            /* size_x = 1, size_y = 1, therefore Z = local index */
-            if (b->shader->info.workgroup_size[0] == 1 &&
-                b->shader->info.workgroup_size[1] == 1)
-               return nir_vec3(b, nir_imm_int(b, 0), nir_imm_int(b, 0), local_index);
-
-            /* size_x = 1, size_z = 1, therefore Y = local index */
-            if (b->shader->info.workgroup_size[0] == 1 &&
-                b->shader->info.workgroup_size[2] == 1)
-               return nir_vec3(b, nir_imm_int(b, 0), local_index, nir_imm_int(b, 0));
-
-            /* size_y = 1, size_z = 1, therefore X = local index */
-            if (b->shader->info.workgroup_size[1] == 1 &&
-                b->shader->info.workgroup_size[2] == 1)
-               return nir_vec3(b, local_index, nir_imm_int(b, 0), nir_imm_int(b, 0));
+            nir_ssa_def *val = try_lower_id_to_index_1d(b, local_index,
+                  b->shader->info.workgroup_size);
+            if (val)
+               return val;
          }
 
          nir_ssa_def *local_size = nir_load_workgroup_size(b);