diff --git a/CMakeLists.txt b/CMakeLists.txt
index 22cf520c..721ebb30 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -338,29 +338,21 @@ endif()
 if(SIZEOF_UNSIGNED_INT EQUAL SIZEOF_SIZE_T)
   set(TIFF_SIZE_T "unsigned int")
   set(TIFF_SIZE_FORMAT "%u")
+  set(TIFF_SSIZE_T "signed int")
+  set(TIFF_SSIZE_FORMAT "%d")
 elseif(SIZEOF_UNSIGNED_LONG EQUAL SIZEOF_SIZE_T)
   set(TIFF_SIZE_T "unsigned long")
   set(TIFF_SIZE_FORMAT "%lu")
-elseif(SIZEOF_UNSIGNED_LONG_LONG EQUAL SIZEOF_SIZE_T)
-  set(TIFF_SIZE_T "unsigned long long")
-  if (MINGW)
-    set(TIFF_SIZE_FORMAT "%I64u")
-  else()
-    set(TIFF_SIZE_FORMAT "%llu")
-  endif()
-endif()
-
-if(SIZEOF_SIGNED_INT EQUAL SIZEOF_UNSIGNED_CHAR_P)
-  set(TIFF_SSIZE_T "signed int")
-  set(TIFF_SSIZE_FORMAT "%d")
-elseif(SIZEOF_SIGNED_LONG EQUAL SIZEOF_UNSIGNED_CHAR_P)
   set(TIFF_SSIZE_T "signed long")
   set(TIFF_SSIZE_FORMAT "%ld")
-elseif(SIZEOF_SIGNED_LONG_LONG EQUAL SIZEOF_UNSIGNED_CHAR_P)
+elseif(SIZEOF_UNSIGNED_LONG_LONG EQUAL SIZEOF_SIZE_T)
+  set(TIFF_SIZE_T "unsigned long long")
   set(TIFF_SSIZE_T "signed long long")
   if (MINGW)
+    set(TIFF_SIZE_FORMAT "%I64u")
     set(TIFF_SSIZE_FORMAT "%I64d")
   else()
+    set(TIFF_SIZE_FORMAT "%llu")
     set(TIFF_SSIZE_FORMAT "%lld")
   endif()
 endif()
diff --git a/configure.ac b/configure.ac
index 54915e05..09f959f8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -365,15 +365,15 @@ AC_DEFINE_UNQUOTED([TIFF_SIZE_FORMAT],[$SIZE_FORMAT],[Size type formatter])
 AC_MSG_CHECKING(for signed size type)
 SSIZE_T='unknown'
 SSIZE_FORMAT='unknown'
-if test $ac_cv_sizeof_signed_int -eq $ac_cv_sizeof_unsigned_char_p
+if test $ac_cv_sizeof_signed_int -eq $ac_cv_sizeof_size_t
 then
   SSIZE_T='signed int'
   SSIZE_FORMAT='"%d"'
-elif test $ac_cv_sizeof_signed_long -eq $ac_cv_sizeof_unsigned_char_p
+elif test $ac_cv_sizeof_signed_long -eq $ac_cv_sizeof_size_t
 then
   SSIZE_T='signed long'
   SSIZE_FORMAT='"%ld"'
-elif test $ac_cv_sizeof_signed_long_long -eq $ac_cv_sizeof_unsigned_char_p
+elif test $ac_cv_sizeof_signed_long_long -eq $ac_cv_sizeof_size_t
 then
   SSIZE_T='signed long long'
   case "${host_os}" in
diff --git a/test/testtypes.c b/test/testtypes.c
index 100b7766..a36d21e5 100644
--- a/test/testtypes.c
+++ b/test/testtypes.c
@@ -51,7 +51,7 @@ main()
 	CHECK_TYPE(TIFF_UINT32_T, 4)
 	CHECK_TYPE(TIFF_UINT64_T, 8)
 	CHECK_TYPE(TIFF_SIZE_T, sizeof(size_t))
-	CHECK_TYPE(TIFF_SSIZE_T, sizeof(unsigned char *))
+	CHECK_TYPE(TIFF_SSIZE_T, sizeof(size_t))
 	return 0;
 }