--- build/icu.old/source/common/uposixdefs.h
+++ build/icu/source/common/uposixdefs.h
@@ -52,7 +52,7 @@
  *
  * z/OS needs this definition for timeval and to get usleep.
  */
-#if !defined(_XOPEN_SOURCE_EXTENDED)
+#if !defined(_XOPEN_SOURCE_EXTENDED) && (defined(__IBMC__) || defined(__IBMCPP__))
 #   define _XOPEN_SOURCE_EXTENDED 1
 #endif