diff --git a/skeletons/asn_system.h b/skeletons/asn_system.h
index b1e0212..51af1df 100644
--- a/skeletons/asn_system.h
+++ b/skeletons/asn_system.h
@@ -1,5 +1,6 @@
 /*-
- * Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Copyright (c) 2003, 2004, 2007 Lev Walkin <vlm@lionet.info>.
+ * All rights reserved.
  * Redistribution and modifications are permitted subject to BSD license.
  */
 /*
@@ -103,6 +104,11 @@
 #endif
 #endif
 
+/* Figure out if thread safety is requested */
+#if	!defined(ASN_THREAD_SAFE) && (defined(THREAD_SAFE) || define(_REENTRANT))
+#define	ASN_THREAD_SAFE
+#endif	/* Thread safety */
+
 #ifndef	offsetof	/* If not defined by <stddef.h> */
 #define	offsetof(s, m)	((ptrdiff_t)&(((s *)0)->m) - (ptrdiff_t)((s *)0))
 #endif	/* offsetof */