diff --git a/TODO b/TODO
index 476506fd..2d4cbab6 100644
--- a/TODO
+++ b/TODO
@@ -1,12 +1,12 @@
 Core
 ~~~~
 * right usage of DBG vs. debug
-* cleanup debugging calls!
+* cleanup debugging calls
+* logging and tracing; use appropriate log levels
+* check log calls for trailing newlines
 
 - TOS not supported by kernel -> automatically drop routes with TOS<>0
 
-- use -freg-struct-return ?
-
 - fake multipath?
 - replace all NUM's by expr's
 - config file: define ipaddr constants?
@@ -25,6 +25,8 @@ Core
 - static: check validity of route destination?
 - static: device routes
 
+- device: configuration of interface patterns
+
 - filter: logging of dropped routes (?)
 - limitation of memory consumption: per-process and total (?)
 - adding of route: check whether all bits not covered by masklen are zero
diff --git a/lib/birdlib.h b/lib/birdlib.h
index 4b8164bd..f377a99b 100644
--- a/lib/birdlib.h
+++ b/lib/birdlib.h
@@ -27,13 +27,17 @@
 
 void log(char *msg, ...);
 void die(char *msg, ...) NORET;
+void bug(char *msg, ...) NORET;
 
 #define L_DEBUG "\001"			/* Debugging messages */
-#define L_INFO "\002"			/* Informational messages */
-#define L_WARN "\003"			/* Warnings */
-#define L_ERR "\004"			/* Errors */
-#define L_AUTH "\005"			/* Authorization failed etc. */
-#define L_FATAL "\006"			/* Fatal errors */
+#define L_TRACE "\002"			/* Protocol tracing */
+#define L_INFO "\003"			/* Informational messages */
+#define L_REMOTE "\004"			/* Remote protocol errors */
+#define L_WARN "\004"			/* Local warnings */
+#define L_ERR "\005"			/* Local errors */
+#define L_AUTH "\006"			/* Authorization failed etc. */
+#define L_FATAL "\007"			/* Fatal errors */
+#define L_BUG "\010"			/* BIRD bugs */
 
 void log_init(char *);			/* Initialize logging to given file (NULL=stderr, ""=syslog) */
 void log_init_debug(char *);		/* Initialize debug dump to given file (NULL=stderr, ""=off) */
@@ -48,4 +52,10 @@ void debug(char *msg, ...);		/* Printf to debug output */
 #define DBG(x, y...)
 #endif
 
+#ifdef DEBUGGING
+#define ASSERT(x) do { if (!(x)) bug("Assertion `%s' failed at %s:%d", #x, __FILE__, __LINE__); } while(0)
+#else
+#define ASSERT(x) do { } while(0)
+#endif
+
 #endif
diff --git a/sysdep/unix/log.c b/sysdep/unix/log.c
index 00589a3c..5dd7ef7f 100644
--- a/sysdep/unix/log.c
+++ b/sysdep/unix/log.c
@@ -107,19 +107,29 @@ log(char *msg, ...)
   va_list args;
 
   va_start(args, msg);
-  if (*msg >= 1 && *msg <= 6)
+  if (*msg >= 1 && *msg <= 8)
     class = *msg++;
   vlog(class, msg, args);
   va_end(args);
 }
 
+void
+bug(char *msg, ...)
+{
+  va_list args;
+
+  va_start(args, msg);
+  vlog(L_BUG[0], msg, args);
+  exit(1);
+}
+
 void
 die(char *msg, ...)
 {
   va_list args;
 
   va_start(args, msg);
-  vlog(6, msg, args);
+  vlog(L_FATAL[0], msg, args);
   exit(1);
 }