diff --git a/googletest/include/gtest/internal/gtest-port.h b/googletest/include/gtest/internal/gtest-port.h
index 4f0d89d0..cd64edf4 100644
--- a/googletest/include/gtest/internal/gtest-port.h
+++ b/googletest/include/gtest/internal/gtest-port.h
@@ -607,7 +607,8 @@ typedef struct _RTL_CRITICAL_SECTION GTEST_CRITICAL_SECTION;
      defined(GTEST_OS_NETBSD) || defined(GTEST_OS_FUCHSIA) ||         \
      defined(GTEST_OS_DRAGONFLY) || defined(GTEST_OS_GNU_KFREEBSD) || \
      defined(GTEST_OS_OPENBSD) || defined(GTEST_OS_HAIKU) ||          \
-     defined(GTEST_OS_GNU_HURD))
+     defined(GTEST_OS_GNU_HURD) || defined(GTEST_OS_SOLARIS) ||       \
+     defined(GTEST_OS_AIX) || defined(GTEST_OS_ZOS))
 #define GTEST_HAS_PTHREAD 1
 #else
 #define GTEST_HAS_PTHREAD 0