old mode 100644
new mode 100755
--- a/security/pkix/test/lib/pkixtestutil.cpp
+++ b/security/pkix/test/lib/pkixtestutil.cpp
@@ -244,17 +244,17 @@ Integer(long value)
   ByteString encodedValue;
   encodedValue.push_back(static_cast<uint8_t>(value));
   return TLV(der::INTEGER, encodedValue);
 }
 
 enum TimeEncoding { UTCTime = 0, GeneralizedTime = 1 };
 
 // Windows doesn't provide gmtime_r, but it provides something very similar.
-#if defined(WIN32) && !defined(_POSIX_THREAD_SAFE_FUNCTIONS)
+#if defined(WIN32) && (!defined(_POSIX_C_SOURCE) || !defined(_POSIX_THREAD_SAFE_FUNCTIONS))
 static tm*
 gmtime_r(const time_t* t, /*out*/ tm* exploded)
 {
   if (gmtime_s(exploded, t) != 0) {
     return nullptr;
   }
   return exploded;
 }