Index: locks/unix/proc_mutex.c
===================================================================
--- locks/unix/proc_mutex.c	(revision 595800)
+++ locks/unix/proc_mutex.c	(working copy)
@@ -426,7 +426,7 @@
     apr_status_t rv;
  
     if ((rv = pthread_mutex_trylock(mutex->pthread_interproc))) {
-#ifdef PTHREAD_SETS_ERRNO
+#ifdef HAVE_ZOS_PTHREADS 
         rv = errno;
 #endif
         if (rv == EBUSY) {