diff --git a/src/system_wrappers/source/system_wrappers.gyp b/src/system_wrappers/source/system_wrappers.gyp
index f834709138..7a3cd20905 100644
--- a/src/system_wrappers/source/system_wrappers.gyp
+++ b/src/system_wrappers/source/system_wrappers.gyp
@@ -226,7 +226,7 @@
             }, {
               'sources!': [ 'data_log_unittest.cc', ],
             }],
-            ['os_posix!=1', {
+            ['os_posix==0', {
               'sources!': [ 'thread_posix_unittest.cc', ],
             }],
           ],