--- a/src/utils.h
+++ b/src/utils.h
@@ -37,37 +37,38 @@
 extern char *strsave (const char *);
 extern char *strconcat (const char *, const char *);
 extern void discard_until (istream&, char);
-extern void check_dimensions (int& nr, int& nc, char *warnfor);
+extern void check_dimensions (int& nr, int& nc, const char *warnfor);
 extern void raw_mode (int);
 extern int kbhit (void);
 extern char **pathstring_to_vector (char *);
 extern char *default_path (void);
 extern char *get_site_defaults (void);
 extern char *default_pager (void);
-extern char *file_in_path (char *, char *);
-extern char *m_file_in_path (char *);
-extern char *polite_directory_format (char *);
-extern int absolute_pathname (char *);
-extern int absolute_program (char *);
+extern char *file_in_path (const char *, const char *);
+extern char *m_file_in_path (const char *);
+extern char *polite_directory_format (const char *);
+extern int absolute_pathname (const char *);
+extern int absolute_program (const char *);
 extern char *base_pathname (char *);
-extern int read_octal (char *);
+extern int read_octal (const char *);
 extern char *sub_append_string (char *, char *, int *, int *);
-extern char *decode_prompt_string (char *);
+extern char *decode_prompt_string (const char *);
 extern void pathname_backup (char *, int);
-extern char *make_absolute (char *, char *);
-extern char *get_working_directory (char *);
-extern int change_to_directory (char *);
-extern int is_newer (char *, time_t);
+extern char *make_absolute (const char *, const char *);
+extern char *get_working_directory (const char *);
+extern int change_to_directory (const char *);
+extern int is_newer (const char *, time_t);
 extern void volatile jump_to_top_level (void);
 extern char *s_plural (int);
 extern char *es_plural (int);
-extern char *save_in_tmp_file (tree_constant& t, int nd = 2, int para = 0);
+extern char *save_in_tmp_file (tree_constant& t, int nd = 2, int para = 0); 
 extern void mark_for_deletion (const char *);
 extern void cleanup_tmp_files (void);
 extern int send_to_plot_stream (const char *cmd);
 extern void close_plot_stream (void);
-extern int almost_match (char *std, char *s, int min_match_len = 1);
-extern char **get_m_file_names (int& mfl_len, char *dir, int no_suffix);
+extern int almost_match (const char *std, const char *s,
+			 int min_match_len = 1); 
+extern char **get_m_file_names (int& mfl_len, const char *dir, int no_suffix);
 extern char **get_m_file_names (int& mfl_len, int no_suffix);
 extern int NINT (double x);
 extern double D_NINT (double x);