diff --git a/client/util.c b/client/util.c
index 451bb60c..050224b9 100644
--- a/client/util.c
+++ b/client/util.c
@@ -17,7 +17,7 @@
 /* Client versions of logging functions */
 
 static void
-vlog(char *msg, va_list args)
+vlog(const char *msg, va_list args)
 {
   char buf[1024];
 
@@ -28,7 +28,7 @@ vlog(char *msg, va_list args)
 }
 
 void
-bug(char *msg, ...)
+bug(const char *msg, ...)
 {
   va_list args;
 
@@ -41,7 +41,7 @@ bug(char *msg, ...)
 }
 
 void
-die(char *msg, ...)
+die(const char *msg, ...)
 {
   va_list args;
 
diff --git a/lib/birdlib.h b/lib/birdlib.h
index 84a6c1b4..d107c399 100644
--- a/lib/birdlib.h
+++ b/lib/birdlib.h
@@ -128,10 +128,10 @@ typedef struct buffer {
 
 #define log log_msg
 void log_commit(int class, buffer *buf);
-void log_msg(char *msg, ...);
-void log_rl(struct tbf *rl, char *msg, ...);
-void die(char *msg, ...) NORET;
-void bug(char *msg, ...) NORET;
+void log_msg(const char *msg, ...);
+void log_rl(struct tbf *rl, const char *msg, ...);
+void die(const char *msg, ...) NORET;
+void bug(const char *msg, ...) NORET;
 
 #define L_DEBUG "\001"			/* Debugging messages */
 #define L_TRACE "\002"			/* Protocol tracing */
@@ -143,7 +143,7 @@ void bug(char *msg, ...) NORET;
 #define L_FATAL "\010"			/* Fatal errors */
 #define L_BUG "\011"			/* BIRD bugs */
 
-void debug(char *msg, ...);		/* Printf to debug output */
+void debug(const char *msg, ...);		/* Printf to debug output */
 
 /* Debugging */
 
diff --git a/sysdep/unix/log.c b/sysdep/unix/log.c
index 3ae98df8..7cb26360 100644
--- a/sysdep/unix/log.c
+++ b/sysdep/unix/log.c
@@ -163,7 +163,7 @@ vlog(int class, const char *msg, va_list args)
  * It is essentially a sequence of log_reset(), logn() and log_commit().
  */
 void
-log_msg(char *msg, ...)
+log_msg(const char *msg, ...)
 {
   int class = 1;
   va_list args;
@@ -176,7 +176,7 @@ log_msg(char *msg, ...)
 }
 
 void
-log_rl(struct tbf *f, char *msg, ...)
+log_rl(struct tbf *f, const char *msg, ...)
 {
   int last_hit = f->mark;
   int class = 1;
@@ -202,7 +202,7 @@ log_rl(struct tbf *f, char *msg, ...)
  * of the program.
  */
 void
-bug(char *msg, ...)
+bug(const char *msg, ...)
 {
   va_list args;
 
@@ -219,7 +219,7 @@ bug(char *msg, ...)
  * of the program.
  */
 void
-die(char *msg, ...)
+die(const char *msg, ...)
 {
   va_list args;
 
@@ -236,7 +236,7 @@ die(char *msg, ...)
  * to the debugging output. No newline character is appended.
  */
 void
-debug(char *msg, ...)
+debug(const char *msg, ...)
 {
   va_list args;
   char buf[1024];