1 files changed, 1 insertions, 1 deletions
diff --git a/vm_dump.c b/vm_dump.c
index 2ed3f1431b..bb2b2415c4 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -432,7 +432,7 @@ rb_vmdebug_thread_dump_state(VALUE self)
 }
 
 #if defined(HAVE_BACKTRACE)
-# if HAVE_LIBUNWIND
+# ifdef HAVE_LIBUNWIND
 #  undef backtrace
 #  define backtrace unw_backtrace
 # elif defined(__APPLE__) && defined(__x86_64__)