diff --git a/libmesosphere/include/mesosphere/kern_select_cpu.hpp b/libmesosphere/include/mesosphere/kern_select_cpu.hpp
index 55e030bd..58945e6f 100644
--- a/libmesosphere/include/mesosphere/kern_select_cpu.hpp
+++ b/libmesosphere/include/mesosphere/kern_select_cpu.hpp
@@ -70,7 +70,7 @@ namespace ams::kern {
         static constexpr inline u64 ConvertVirtualCoreMaskToPhysical(u64 v_core_mask) {
             u64 p_core_mask = 0;
             while (v_core_mask != 0) {
-                const u64 next = __builtin_ctzll(v_core_mask);
+                const u64 next = util::CountTrailingZeros(v_core_mask);
                 v_core_mask &= ~(static_cast<u64>(1) << next);
                 p_core_mask |=  (static_cast<u64>(1) << cpu::VirtualToPhysicalCoreMap[next]);
             }