diff --git a/zlib.h b/zlib.h
index 6fed1b3..592d453 100644
--- a/zlib.h
+++ b/zlib.h
@@ -1891,9 +1891,9 @@ ZEXTERN int ZEXPORT gzgetc_(gzFile file);       /* backward compatibility */
      ZEXTERN z_off_t ZEXPORT gzseek64(gzFile, z_off_t, int);
      ZEXTERN z_off_t ZEXPORT gztell64(gzFile);
      ZEXTERN z_off_t ZEXPORT gzoffset64(gzFile);
-     ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off_t);
-     ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off_t);
-     ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off_t);
+     ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off64_t);
+     ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off64_t);
+     ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off64_t);
 #  endif
 #else
    ZEXTERN gzFile ZEXPORT gzopen(const char *, const char *);
diff --git a/zutil.h b/zutil.h
index 630bc11..4f22299 100644
--- a/zutil.h
+++ b/zutil.h
@@ -168,11 +168,10 @@ extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
 #endif
 
 /* provide prototypes for these when building zlib without LFS */
-#if !defined(_WIN32) && \
-    (!defined(_LARGEFILE64_SOURCE) || _LFS64_LARGEFILE-0 == 0)
-    ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off_t);
-    ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off_t);
-    ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off_t);
+#ifndef Z_LARGE64
+   ZEXTERN uLong ZEXPORT adler32_combine64(uLong, uLong, z_off64_t);
+   ZEXTERN uLong ZEXPORT crc32_combine64(uLong, uLong, z_off64_t);
+   ZEXTERN uLong ZEXPORT crc32_combine_gen64(z_off64_t);
 #endif
 
         /* common defaults */