-extern long scm_num2long SCM_P ((SCM num, char *pos, char *s_caller));
-extern long_long scm_num2long_long SCM_P ((SCM num, char *pos, char *s_caller));
-extern unsigned long scm_num2ulong SCM_P ((SCM num, char *pos, char *s_caller));
+extern long scm_num2long SCM_P ((SCM num, char *pos, const char *s_caller));
+extern long_long scm_num2long_long SCM_P ((SCM num, char *pos,
+ const char *s_caller));
+extern unsigned long scm_num2ulong SCM_P ((SCM num, char *pos,
+ const char *s_caller));