diff --git a/src/impl/list_ports/list_ports_osx.cc b/src/impl/list_ports/list_ports_osx.cc
index fa1aeb8..29da120 100644
--- a/src/impl/list_ports/list_ports_osx.cc
+++ b/src/impl/list_ports/list_ports_osx.cc
@@ -1,4 +1,4 @@
-#if defined(_APPLE_)
+#if defined(__APPLE__)
 
 #include <sys/param.h>
 #include <stdint.h>
@@ -282,4 +282,4 @@ serial::list_ports(void)
     return devices_found;
 }
 
-#endif // defined(_APPLE_)
+#endif // defined(__APPLE__)