diff --git a/skeletons/asn_internal.h b/skeletons/asn_internal.h
index 3f99452..674ed51 100644
--- a/skeletons/asn_internal.h
+++ b/skeletons/asn_internal.h
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2003, 2004, 2005 Lev Walkin <vlm@lionet.info>.
+ * Copyright (c) 2003, 2004, 2005, 2007 Lev Walkin <vlm@lionet.info>.
  * All rights reserved.
  * Redistribution and modifications are permitted subject to BSD license.
  */
@@ -35,10 +35,17 @@
 #ifndef	ASN_DEBUG	/* If debugging code is not defined elsewhere... */
 #if	EMIT_ASN_DEBUG == 1	/* And it was asked to emit this code... */
 #ifdef	__GNUC__
-#define	ASN_DEBUG(fmt, args...)	do {		\
-		fprintf(stderr, fmt, ##args);	\
-		fprintf(stderr, " (%s:%d)\n",	\
-			__FILE__, __LINE__);	\
+#ifdef	ASN_THREAD_SAFE
+#define	asn_debug_indent	0
+#endif
+int asn_debug_indent;
+#endif
+#define	ASN_DEBUG(fmt, args...)	do {			\
+		int adi = asn_debug_indent;		\
+		while(adi--) fprintf(stderr, " ");	\
+		fprintf(stderr, fmt, ##args);		\
+		fprintf(stderr, " (%s:%d)\n",		\
+			__FILE__, __LINE__);		\
 	} while(0)
 #else	/* !__GNUC__ */
 void ASN_DEBUG_f(const char *fmt, ...);
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 */