diff --git a/crc32.c b/crc32.c
index c71a689..f8357b0 100644
--- a/crc32.c
+++ b/crc32.c
@@ -98,13 +98,22 @@
 #  endif
 #endif
 
+/* If available, use the ARM processor CRC32 instruction. */
+#if defined(__aarch64__) && defined(__ARM_FEATURE_CRC32) && W == 8
+#  define ARMCRC32
+#endif
+
 /* Local functions. */
 local z_crc_t multmodp OF((z_crc_t a, z_crc_t b));
 local z_crc_t x2nmodp OF((z_off64_t n, unsigned k));
 
-/* If available, use the ARM processor CRC32 instruction. */
-#if defined(__aarch64__) && defined(__ARM_FEATURE_CRC32) && W == 8
-#  define ARMCRC32
+#if defined(W) && (!defined(ARMCRC32) || defined(DYNAMIC_CRC_TABLE))
+    local z_word_t byte_swap OF((z_word_t word));
+#endif
+
+#if defined(W) && !defined(ARMCRC32)
+    local z_crc_t crc_word OF((z_word_t data));
+    local z_word_t crc_word_big OF((z_word_t data));
 #endif
 
 #if defined(W) && (!defined(ARMCRC32) || defined(DYNAMIC_CRC_TABLE))
diff --git a/zutil.h b/zutil.h
index d9a20ae..0bc7f4e 100644
--- a/zutil.h
+++ b/zutil.h
@@ -193,6 +193,7 @@ extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
     (!defined(_LARGEFILE64_SOURCE) || _LFS64_LARGEFILE-0 == 0)
     ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
     ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
+    ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off_t));
 #endif
 
         /* common defaults */