diff --git a/src/core/ngx_string.h b/src/core/ngx_string.h
index 1bca791..4fe5cb6 100644
--- a/src/core/ngx_string.h
+++ b/src/core/ngx_string.h
@@ -141,7 +141,7 @@
 time_t ngx_atotm(u_char *line, size_t n);
 ngx_int_t ngx_hextoi(u_char *line, size_t n);
 
-void ngx_md5_text(u_char *text, u_char *md5);
+u_char *ngx_hex_dump(u_char *dst, u_char *src, size_t len);
 
 
 #define ngx_base64_encoded_length(len)  (((len + 2) / 3) * 4)