diff --git a/slang/ChangeLog b/slang/ChangeLog
index 727c4c928..c14d61547 100644
--- a/slang/ChangeLog
+++ b/slang/ChangeLog
@@ -1,3 +1,7 @@
+2004-08-29  Roland Illig  <roland.illig@gmx.de>
+
+	* slang.h: Added const qualifier to some of the SLang functions.
+
 2003-09-26  Andrew V. Samoilov  <sav@bcs.zp.ua>
 
 	* sldisply.c (RGB_to_BGR): Make const.
diff --git a/slang/include/slang.h b/slang/include/slang.h
index af7a1592c..8dc568449 100644
--- a/slang/include/slang.h
+++ b/slang/include/slang.h
@@ -697,7 +697,7 @@ extern void SLang_vmessage (char *, ...);
      messages are displayed on stderr. */
 
   extern void (*SLang_Exit_Error_Hook)(char *, va_list);
-  extern void SLang_exit_error (char *, ...);
+  extern void SLang_exit_error (const char *, ...);
   extern void (*SLang_Dump_Routine)(char *);
   /* Called if S-Lang traceback is enabled as well as other debugging
      routines (e.g., trace).  By default, these messages go to stderr. */
@@ -1297,22 +1297,22 @@ extern void SLtt_disable_status_line (void);
 /* These are termcap/terminfo routines that assume SLtt_initialize has
  * been called.
  */
-extern char *SLtt_tgetstr (char *);
-extern int SLtt_tgetnum (char *);
-extern int SLtt_tgetflag (char *);
+extern char *SLtt_tgetstr (const char *);
+extern int SLtt_tgetnum (const char *);
+extern int SLtt_tgetflag (const char *);
 
 /* The following are terminfo-only routines -- these prototypes will change
  * in V2.x.
  */
 extern char *SLtt_tigetent (char *);
-extern char *SLtt_tigetstr (char *, char **);
+extern char *SLtt_tigetstr (const char *, char **);
 extern int SLtt_tigetnum (char *, char **);
 # endif
 #endif
 
 extern SLtt_Char_Type SLtt_get_color_object (int);
 extern void SLtt_set_color_object (int, SLtt_Char_Type);
-extern void SLtt_set_color (int, char *, char *, char *);
+extern void SLtt_set_color (int, const char *, const char *, const char *);
 extern void SLtt_set_mono (int, char *, SLtt_Char_Type);
 extern void SLtt_add_color_attribute (int, SLtt_Char_Type);
 extern void SLtt_set_color_fgbg (int, SLtt_Char_Type, SLtt_Char_Type);
@@ -1359,12 +1359,12 @@ extern void SLsmg_erase_eos (void);
 extern void SLsmg_reverse_video (void);
 extern void SLsmg_set_color (int);
 extern void SLsmg_normal_video (void);
-extern void SLsmg_printf (char *, ...);
-extern void SLsmg_vprintf (char *, va_list);
-extern void SLsmg_write_string (char *);
+extern void SLsmg_printf (const char *, ...);
+extern void SLsmg_vprintf (const char *, va_list);
+extern void SLsmg_write_string (const char *);
 extern void SLsmg_write_nstring (char *, unsigned int);
 extern void SLsmg_write_char (char);
-extern void SLsmg_write_nchars (char *, unsigned int);
+extern void SLsmg_write_nchars (const char *, unsigned int);
 extern void SLsmg_write_wrapped_string (char *, int, int, unsigned int, unsigned int, int);
 extern void SLsmg_cls (void);
 extern void SLsmg_refresh (void);
diff --git a/slang/sldisply.c b/slang/sldisply.c
index 635753216..866610d2d 100644
--- a/slang/sldisply.c
+++ b/slang/sldisply.c
@@ -1195,7 +1195,7 @@ static int make_color_fgbg (char *fg, char *bg, SLtt_Char_Type *fgbg)
    return 0;
 }
 
-void SLtt_set_color (int obj, char *what, char *fg, char *bg)
+void SLtt_set_color (int obj, const char *what, const char *fg, const char *bg)
 {
    SLtt_Char_Type fgbg;
 
@@ -2022,7 +2022,7 @@ static char *fixup_tgetstr (char *what)
    return what;
 }
 
-char *SLtt_tgetstr (char *cap)
+char *SLtt_tgetstr (const char *cap)
 {
    char *s;
 
@@ -2045,7 +2045,7 @@ char *SLtt_tgetstr (char *cap)
    return fixup_tgetstr (s);
 }
 
-int SLtt_tgetnum (char *s)
+int SLtt_tgetnum (const char *s)
 {
    if (Termcap_Initalized == 0)
      return -1;
@@ -2056,7 +2056,7 @@ int SLtt_tgetnum (char *s)
 #endif
 }
 
-int SLtt_tgetflag (char *s)
+int SLtt_tgetflag (const char *s)
 {
    if (Termcap_Initalized == 0)
      return -1;
diff --git a/slang/slerr.c b/slang/slerr.c
index 896392a56..a7f6c7923 100644
--- a/slang/slerr.c
+++ b/slang/slerr.c
@@ -139,7 +139,7 @@ void SLang_verror (int err_code, char *fmt, ...)
    SLang_doerror (fmt);
 }
 
-void SLang_exit_error (char *fmt, ...)
+void SLang_exit_error (const char *fmt, ...)
 {
    va_list ap;
 
diff --git a/slang/slsmg.c b/slang/slsmg.c
index f1c580988..dd72b1cb3 100644
--- a/slang/slsmg.c
+++ b/slang/slsmg.c
@@ -220,7 +220,7 @@ static int point_visible (int col_too)
 		   && (This_Col < Start_Col + Screen_Cols))));
 }
 
-void SLsmg_write_string (char *str)
+void SLsmg_write_string (const char *str)
 {
    SLsmg_write_nchars (str, strlen (str));
 }
@@ -302,7 +302,7 @@ static unsigned char Alt_Char_Set[129];/* 129th is used as a flag */
 int SLsmg_Display_Eight_Bit = 128;
 #endif
 
-void SLsmg_write_nchars (char *str, unsigned int n)
+void SLsmg_write_nchars (const char *str, unsigned int n)
 {
    register SLsmg_Char_Type *p, old, neew, color;
    unsigned char ch;
@@ -1177,7 +1177,7 @@ SLsmg_Char_Type SLsmg_char_at (void)
    return 0;
 }
 
-void SLsmg_vprintf (char *fmt, va_list ap)
+void SLsmg_vprintf (const char *fmt, va_list ap)
 {
    char buf[1024];
 
@@ -1187,7 +1187,7 @@ void SLsmg_vprintf (char *fmt, va_list ap)
    SLsmg_write_string (buf);
 }
 
-void SLsmg_printf (char *fmt, ...)
+void SLsmg_printf (const char *fmt, ...)
 {
    va_list ap;
    unsigned int len;
diff --git a/slang/sltermin.c b/slang/sltermin.c
index 598421902..1d5106078 100644
--- a/slang/sltermin.c
+++ b/slang/sltermin.c
@@ -1147,7 +1147,7 @@ char *SLtt_tigetent (char *s)
    return (char *) _SLtt_tigetent (s);
 }
 
-extern char *SLtt_tigetstr (char *s, char **p)
+extern char *SLtt_tigetstr (const char *s, char **p)
 {
    if (p == NULL)
      return NULL;