diff --git a/sys/contrib/zlib/crc32.c b/sys/contrib/zlib/crc32.c
--- a/sys/contrib/zlib/crc32.c
+++ b/sys/contrib/zlib/crc32.c
@@ -114,6 +114,8 @@
   instruction, if one is available. This assumes that word_t is either 32 bits
   or 64 bits.
  */
+local z_word_t byte_swap OF((z_word_t word));
+
 local z_word_t byte_swap(word)
     z_word_t word;
 {
@@ -714,6 +716,8 @@
   least-significant byte of the word as the first byte of data, without any pre
   or post conditioning. This is used to combine the CRCs of each braid.
  */
+local z_crc_t crc_word OF((z_word_t data));
+
 local z_crc_t crc_word(data)
     z_word_t data;
 {
@@ -723,6 +727,8 @@
     return (z_crc_t)data;
 }
 
+local z_word_t crc_word_big OF((z_word_t data));
+
 local z_word_t crc_word_big(data)
     z_word_t data;
 {