diff --git a/lib/System/Unix/Program.inc b/lib/System/Unix/Program.inc
index 1fe25861e1e..4da1c73fbd1 100644
--- a/lib/System/Unix/Program.inc
+++ b/lib/System/Unix/Program.inc
@@ -125,11 +125,13 @@ static void SetMemoryLimits (unsigned size)
   r.rlim_cur = limit;
   setrlimit (RLIMIT_RSS, &r);
 #endif
+#ifdef RLIMIT_AS  // e.g. NetBSD doesn't have it.
   // Virtual memory.
   getrlimit (RLIMIT_AS, &r);
   r.rlim_cur = limit;
   setrlimit (RLIMIT_AS, &r);
 #endif
+#endif
 }
 
 int