diff --git a/crc32.c b/crc32.c
index 9580440..e72636a 100644
--- a/crc32.c
+++ b/crc32.c
@@ -212,7 +212,7 @@
 #endif /* DYNAMIC_CRC_TABLE */
 
 #ifdef BYFOUR
-    if (sizeof(void *) == sizeof(ptrdiff_t)) {
+    if (sizeof(void *) == sizeof(z_size_t)) {
         z_crc_t endian;
 
         endian = 1;
@@ -273,7 +273,7 @@
 
     c = (z_crc_t)crc;
     c = ~c;
-    while (len && ((ptrdiff_t)buf & 3)) {
+    while (len && ((z_size_t)buf & 3)) {
         c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);
         len--;
     }
@@ -313,7 +313,7 @@
 
     c = ZSWAP32((z_crc_t)crc);
     c = ~c;
-    while (len && ((ptrdiff_t)buf & 3)) {
+    while (len && ((z_size_t)buf & 3)) {
         c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8);
         len--;
     }
diff --git a/zutil.h b/zutil.h
index b079ea6..60a0bca 100644
--- a/zutil.h
+++ b/zutil.h
@@ -29,10 +29,6 @@
 #  include <stdlib.h>
 #endif
 
-#ifdef Z_SOLO
-   typedef long ptrdiff_t;  /* guess -- will be caught if guess is wrong */
-#endif
-
 #ifndef local
 #  define local static
 #endif
@@ -170,10 +166,6 @@
 #if (defined(_MSC_VER) && (_MSC_VER > 600)) && !defined __INTERIX
 #  if defined(_WIN32_WCE)
 #    define fdopen(fd,mode) NULL /* No fdopen() */
-#    ifndef _PTRDIFF_T_DEFINED
-       typedef int ptrdiff_t;
-#      define _PTRDIFF_T_DEFINED
-#    endif
 #  else
 #    define fdopen(fd,type)  _fdopen(fd,type)
 #  endif