diff --git a/include/sys/resource.h b/include/sys/resource.h
index 0b3478301d..044c75aeff 100644
--- a/include/sys/resource.h
+++ b/include/sys/resource.h
@@ -115,6 +115,7 @@ struct rusage
 {
   struct timeval ru_utime;  /* User time used */
   struct timeval ru_stime;  /* System time used */
+  long           ru_maxrss; /* maximum resident set size */
 };
 
 /****************************************************************************