diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index 0b575ef78..85139c8d9 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -456,6 +456,15 @@
 #endif
 #endif
 
+#ifndef SSIZE_T_MAX
+/* some limits.h headers have this defined, some don't */
+#if defined(SIZEOF_SIZE_T) && (SIZEOF_SIZE_T > 4)
+#define SSIZE_T_MAX 9223372036854775807
+#else
+#define SSIZE_T_MAX 2147483647
+#endif
+#endif
+
 /*
  * Arg 2 type for gethostname in case it hasn't been defined in config file.
  */
diff --git a/lib/warnless.c b/lib/warnless.c
index c0764c42d..15c8156d1 100644
--- a/lib/warnless.c
+++ b/lib/warnless.c
@@ -37,85 +37,23 @@
 
 #include "warnless.h"
 
-#define CURL_MASK_SCHAR  0x7F
-#define CURL_MASK_UCHAR  0xFF
+#define CURL_MASK_UCHAR   ((unsigned char)~0)
+#define CURL_MASK_SCHAR   (CURL_MASK_UCHAR >> 1)
 
-#if (SIZEOF_SHORT == 2)
-#  define CURL_MASK_SSHORT  0x7FFF
-#  define CURL_MASK_USHORT  0xFFFF
-#elif (SIZEOF_SHORT == 4)
-#  define CURL_MASK_SSHORT  0x7FFFFFFF
-#  define CURL_MASK_USHORT  0xFFFFFFFF
-#elif (SIZEOF_SHORT == 8)
-#  define CURL_MASK_SSHORT  0x7FFFFFFFFFFFFFFF
-#  define CURL_MASK_USHORT  0xFFFFFFFFFFFFFFFF
-#else
-#  error "SIZEOF_SHORT not defined"
-#endif
+#define CURL_MASK_USHORT  ((unsigned short)~0)
+#define CURL_MASK_SSHORT  (CURL_MASK_USHORT >> 1)
 
-#if (SIZEOF_INT == 2)
-#  define CURL_MASK_SINT  0x7FFF
-#  define CURL_MASK_UINT  0xFFFF
-#elif (SIZEOF_INT == 4)
-#  define CURL_MASK_SINT  0x7FFFFFFF
-#  define CURL_MASK_UINT  0xFFFFFFFF
-#elif (SIZEOF_INT == 8)
-#  define CURL_MASK_SINT  0x7FFFFFFFFFFFFFFF
-#  define CURL_MASK_UINT  0xFFFFFFFFFFFFFFFF
-#elif (SIZEOF_INT == 16)
-#  define CURL_MASK_SINT  0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
-#  define CURL_MASK_UINT  0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
-#else
-#  error "SIZEOF_INT not defined"
-#endif
+#define CURL_MASK_UINT    ((unsigned int)~0)
+#define CURL_MASK_SINT    (CURL_MASK_UINT >> 1)
 
-#if (SIZEOF_LONG == 2)
-#  define CURL_MASK_SLONG  0x7FFFL
-#  define CURL_MASK_ULONG  0xFFFFUL
-#elif (SIZEOF_LONG == 4)
-#  define CURL_MASK_SLONG  0x7FFFFFFFL
-#  define CURL_MASK_ULONG  0xFFFFFFFFUL
-#elif (SIZEOF_LONG == 8)
-#  define CURL_MASK_SLONG  0x7FFFFFFFFFFFFFFFL
-#  define CURL_MASK_ULONG  0xFFFFFFFFFFFFFFFFUL
-#elif (SIZEOF_LONG == 16)
-#  define CURL_MASK_SLONG  0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFL
-#  define CURL_MASK_ULONG  0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFUL
-#else
-#  error "SIZEOF_LONG not defined"
-#endif
+#define CURL_MASK_ULONG   ((unsigned long)~0)
+#define CURL_MASK_SLONG   (CURL_MASK_ULONG >> 1)
 
-#if (SIZEOF_CURL_OFF_T == 2)
-#  define CURL_MASK_SCOFFT  CURL_OFF_T_C(0x7FFF)
-#  define CURL_MASK_UCOFFT  CURL_OFF_TU_C(0xFFFF)
-#elif (SIZEOF_CURL_OFF_T == 4)
-#  define CURL_MASK_SCOFFT  CURL_OFF_T_C(0x7FFFFFFF)
-#  define CURL_MASK_UCOFFT  CURL_OFF_TU_C(0xFFFFFFFF)
-#elif (SIZEOF_CURL_OFF_T == 8)
-#  define CURL_MASK_SCOFFT  CURL_OFF_T_C(0x7FFFFFFFFFFFFFFF)
-#  define CURL_MASK_UCOFFT  CURL_OFF_TU_C(0xFFFFFFFFFFFFFFFF)
-#elif (SIZEOF_CURL_OFF_T == 16)
-#  define CURL_MASK_SCOFFT  CURL_OFF_T_C(0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)
-#  define CURL_MASK_UCOFFT  CURL_OFF_TU_C(0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)
-#else
-#  error "SIZEOF_CURL_OFF_T not defined"
-#endif
+#define CURL_MASK_UCOFFT  ((unsigned CURL_TYPEOF_CURL_OFF_T)~0)
+#define CURL_MASK_SCOFFT  (CURL_MASK_UCOFFT >> 1)
 
-#if (SIZEOF_SIZE_T == SIZEOF_SHORT)
-#  define CURL_MASK_SSIZE_T  CURL_MASK_SSHORT
-#  define CURL_MASK_USIZE_T  CURL_MASK_USHORT
-#elif (SIZEOF_SIZE_T == SIZEOF_INT)
-#  define CURL_MASK_SSIZE_T  CURL_MASK_SINT
-#  define CURL_MASK_USIZE_T  CURL_MASK_UINT
-#elif (SIZEOF_SIZE_T == SIZEOF_LONG)
-#  define CURL_MASK_SSIZE_T  CURL_MASK_SLONG
-#  define CURL_MASK_USIZE_T  CURL_MASK_ULONG
-#elif (SIZEOF_SIZE_T == SIZEOF_CURL_OFF_T)
-#  define CURL_MASK_SSIZE_T  CURL_MASK_SCOFFT
-#  define CURL_MASK_USIZE_T  CURL_MASK_UCOFFT
-#else
-#  error "SIZEOF_SIZE_T not defined"
-#endif
+#define CURL_MASK_USIZE_T ((size_t)~0)
+#define CURL_MASK_SSIZE_T (CURL_MASK_USIZE_T >> 1)
 
 /*
 ** unsigned long to unsigned short
@@ -207,7 +145,7 @@ unsigned long curlx_uztoul(size_t uznum)
 # pragma warning(disable:810) /* conversion may lose significant bits */
 #endif
 
-#if (SIZEOF_LONG < SIZEOF_SIZE_T)
+#if ULONG_MAX < SIZE_T_MAX
   DEBUGASSERT(uznum <= (size_t) CURL_MASK_ULONG);
 #endif
   return (unsigned long)(uznum & (size_t) CURL_MASK_ULONG);
@@ -228,7 +166,7 @@ unsigned int curlx_uztoui(size_t uznum)
 # pragma warning(disable:810) /* conversion may lose significant bits */
 #endif
 
-#if (SIZEOF_INT < SIZEOF_SIZE_T)
+#if UINT_MAX < SIZE_T_MAX
   DEBUGASSERT(uznum <= (size_t) CURL_MASK_UINT);
 #endif
   return (unsigned int)(uznum & (size_t) CURL_MASK_UINT);
@@ -250,7 +188,7 @@ int curlx_sltosi(long slnum)
 #endif
 
   DEBUGASSERT(slnum >= 0);
-#if (SIZEOF_INT < SIZEOF_LONG)
+#if INT_MAX < LONG_MAX
   DEBUGASSERT((unsigned long) slnum <= (unsigned long) CURL_MASK_SINT);
 #endif
   return (int)(slnum & (long) CURL_MASK_SINT);
@@ -272,7 +210,7 @@ unsigned int curlx_sltoui(long slnum)
 #endif
 
   DEBUGASSERT(slnum >= 0);
-#if (SIZEOF_INT < SIZEOF_LONG)
+#if UINT_MAX < LONG_MAX
   DEBUGASSERT((unsigned long) slnum <= (unsigned long) CURL_MASK_UINT);
 #endif
   return (unsigned int)(slnum & (long) CURL_MASK_UINT);
@@ -352,7 +290,7 @@ int curlx_sztosi(ssize_t sznum)
 #endif
 
   DEBUGASSERT(sznum >= 0);
-#if (SIZEOF_INT < SIZEOF_SIZE_T)
+#if INT_MAX < SSIZE_T_MAX
   DEBUGASSERT((size_t) sznum <= (size_t) CURL_MASK_SINT);
 #endif
   return (int)(sznum & (ssize_t) CURL_MASK_SINT);