diff --git a/src/library/vm/vm.h b/src/library/vm/vm.h
index 73834a98d5..901710438a 100644
--- a/src/library/vm/vm.h
+++ b/src/library/vm/vm.h
@@ -49,7 +49,7 @@ public:
 };
 
 #define LEAN_VM_IS_PTR(obj) ((reinterpret_cast<size_t>(obj) & 1) == 0)
-#define LEAN_VM_BOX(num)    (reinterpret_cast<vm_obj_cell*>((uintptr_t)((num << 1) | 1)))
+#define LEAN_VM_BOX(num)    (reinterpret_cast<vm_obj_cell*>(static_cast<uintptr_t>((num << 1) | 1)))
 #define LEAN_VM_UNBOX(obj)  (reinterpret_cast<size_t>(obj) >> 1)
 
 [[noreturn]] void vm_check_failed(char const * condition);