extern void header_add(int, const char *, ...);
extern void header_add_at_position(BOOL, uschar *, BOOL, int, const char *, ...);
extern void header_remove(int, const uschar *);
-extern BOOL header_testname(header_line *, const uschar *, int, BOOL);
-extern BOOL header_testname_incomplete(header_line *, const uschar *, int, BOOL);
+extern BOOL header_testname(const header_line *, const uschar *, int, BOOL);
+extern BOOL header_testname_incomplete(const header_line *, const uschar *, int, BOOL);
extern void log_write(unsigned int, int, const char *format, ...) PRINTF_FUNCTION(3,4);
extern int lss_b64decode(uschar *, uschar **);
extern uschar *lss_b64encode(uschar *, int);