diff --git a/addon.gypi b/addon.gypi
index 3372bfa521..552e4748d3 100644
--- a/addon.gypi
+++ b/addon.gypi
@@ -99,7 +99,8 @@
           '_FILE_OFFSET_BITS=64'
         ],
       }],
-      [ 'OS=="freebsd" or OS=="openbsd" or OS=="solaris" or (OS=="linux" and target_arch!="ia32")', {
+      [ 'OS in "freebsd openbsd netbsd solaris" or \
+         (OS=="linux" and target_arch!="ia32")', {
         'cflags': [ '-fPIC' ],
       }]
     ]