diff --git a/aria.cpp b/aria.cpp
index c9b7c4f0..b2985656 100644
--- a/aria.cpp
+++ b/aria.cpp
@@ -269,7 +269,7 @@ void ARIA::Base::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, b
 	ARIA_KXL; rk+= 16; ARIA_FO; ARIA_KXL; rk+= 16; ARIA_FE;
 	ARIA_KXL; rk+= 16; ARIA_FO; ARIA_KXL; rk+= 16;
 
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 # if CRYPTOPP_ENABLE_ARIA_SSSE3_INTRINSICS
 	if (HasSSSE3())
 	{
diff --git a/camellia.cpp b/camellia.cpp
index da48caa6..be666fd1 100644
--- a/camellia.cpp
+++ b/camellia.cpp
@@ -60,7 +60,7 @@ NAMESPACE_BEGIN(CryptoPP)
 	ROUND(lh, ll, rh, rl, k0, k1)						\
 	ROUND(rh, rl, lh, ll, k2, k3)
 
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 #define EFI(i) (1-(i))
 #else
 #define EFI(i) (i)
diff --git a/config.h b/config.h
index 585fe14e..0636667a 100644
--- a/config.h
+++ b/config.h
@@ -9,23 +9,23 @@
 // ***************** Important Settings ********************
 
 // define this if running on a big-endian CPU
-#if !defined(IS_LITTLE_ENDIAN) && !defined(IS_BIG_ENDIAN) && (defined(__BIG_ENDIAN__) || (defined(__s390__) || defined(__s390x__) || defined(__zarch__)) || (defined(__m68k__) || defined(__MC68K__)) || defined(__sparc) || defined(__sparc__) || defined(__hppa__) || defined(__MIPSEB__) || defined(__ARMEB__) || (defined(__MWERKS__) && !defined(__INTEL__)))
-#	define IS_BIG_ENDIAN 1
+#if !defined(CRYPTOPP_LITTLE_ENDIAN) && !defined(CRYPTOPP_BIG_ENDIAN) && (defined(__BIG_ENDIAN__) || (defined(__s390__) || defined(__s390x__) || defined(__zarch__)) || (defined(__m68k__) || defined(__MC68K__)) || defined(__sparc) || defined(__sparc__) || defined(__hppa__) || defined(__MIPSEB__) || defined(__ARMEB__) || (defined(__MWERKS__) && !defined(__INTEL__)))
+#	define CRYPTOPP_BIG_ENDIAN 1
 #endif
 
 // define this if running on a little-endian CPU
-// big endian will be assumed if IS_LITTLE_ENDIAN is not defined
-#if !defined(IS_BIG_ENDIAN) && !defined(IS_LITTLE_ENDIAN)
-#	define IS_LITTLE_ENDIAN 1
+// big endian will be assumed if CRYPTOPP_LITTLE_ENDIAN is not defined
+#if !defined(CRYPTOPP_BIG_ENDIAN) && !defined(CRYPTOPP_LITTLE_ENDIAN)
+#	define CRYPTOPP_LITTLE_ENDIAN 1
 #endif
 
 // Sanity checks. Some processors have more than big, little and bi-endian modes. PDP mode, where order results in "4312", should
 // raise red flags immediately. Additionally, mis-classified machines, like (previosuly) S/390, should raise red flags immediately.
-#if defined(IS_BIG_ENDIAN) && defined(__GNUC__) && defined(__BYTE_ORDER__) && (__BYTE_ORDER__ != __ORDER_BIG_ENDIAN__)
-# error "IS_BIG_ENDIAN is set, but __BYTE_ORDER__ is not __ORDER_BIG_ENDIAN__"
+#if defined(CRYPTOPP_BIG_ENDIAN) && defined(__GNUC__) && defined(__BYTE_ORDER__) && (__BYTE_ORDER__ != __ORDER_BIG_ENDIAN__)
+# error "CRYPTOPP_BIG_ENDIAN is set, but __BYTE_ORDER__ is not __ORDER_BIG_ENDIAN__"
 #endif
-#if defined(IS_LITTLE_ENDIAN) && defined(__GNUC__) && defined(__BYTE_ORDER__) && (__BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__)
-# error "IS_LITTLE_ENDIAN is set, but __BYTE_ORDER__ is not __ORDER_LITTLE_ENDIAN__"
+#if defined(CRYPTOPP_LITTLE_ENDIAN) && defined(__GNUC__) && defined(__BYTE_ORDER__) && (__BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__)
+# error "CRYPTOPP_LITTLE_ENDIAN is set, but __BYTE_ORDER__ is not __ORDER_LITTLE_ENDIAN__"
 #endif
 
 // Define this if you want to disable all OS-dependent features,
diff --git a/crc.cpp b/crc.cpp
index 89df19fa..b7d8046e 100644
--- a/crc.cpp
+++ b/crc.cpp
@@ -28,7 +28,7 @@ extern void CRC32C_Update_SSE42(const byte *s, size_t n, word32& c);
 
 /* Table of CRC-32's of all single byte values (made by makecrc.c) */
 const word32 CRC32::m_tab[] = {
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 	0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
 	0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
 	0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
@@ -188,7 +188,7 @@ void CRC32::TruncatedFinal(byte *hash, size_t size)
 // Castagnoli CRC32C (iSCSI)
 
 const word32 CRC32C::m_tab[] = {
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
     0x00000000L, 0xf26b8303L, 0xe13b70f7L, 0x1350f3f4L, 0xc79a971fL,
     0x35f1141cL, 0x26a1e7e8L, 0xd4ca64ebL, 0x8ad958cfL, 0x78b2dbccL,
     0x6be22838L, 0x9989ab3bL, 0x4d43cfd0L, 0xbf284cd3L, 0xac78bf27L,
diff --git a/crc.h b/crc.h
index 61923d58..0334f705 100644
--- a/crc.h
+++ b/crc.h
@@ -13,7 +13,7 @@ NAMESPACE_BEGIN(CryptoPP)
 
 const word32 CRC32_NEGL = 0xffffffffL;
 
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 #define CRC32_INDEX(c) (c & 0xff)
 #define CRC32_SHIFTED(c) (c >> 8)
 #else
diff --git a/gcm.cpp b/gcm.cpp
index 280d588a..a773e3f4 100644
--- a/gcm.cpp
+++ b/gcm.cpp
@@ -407,7 +407,7 @@ size_t GCM_Base::AuthenticateBlocks(const byte *data, size_t len)
 
             #define READ_TABLE_WORD64_COMMON(a, b, c, d)    *(word64 *)(void *)(mulTable+(a*1024)+(b*256)+c+d*8)
 
-            #ifdef IS_LITTLE_ENDIAN
+            #ifdef CRYPTOPP_LITTLE_ENDIAN
                 #if CRYPTOPP_BOOL_SLOW_WORD64
                     word32 z0 = (word32)x0;
                     word32 z1 = (word32)(x0>>32);
@@ -478,7 +478,7 @@ size_t GCM_Base::AuthenticateBlocks(const byte *data, size_t len)
 
             #define READ_TABLE_WORD64_COMMON(a, c, d)    *(word64 *)(void *)(mulTable+(a)*256*16+(c)+(d)*8)
 
-            #ifdef IS_LITTLE_ENDIAN
+            #ifdef CRYPTOPP_LITTLE_ENDIAN
                 #if CRYPTOPP_BOOL_SLOW_WORD64
                     word32 z0 = (word32)x0;
                     word32 z1 = (word32)(x0>>32);
diff --git a/integer.cpp b/integer.cpp
index 732c7962..8eadc47e 100644
--- a/integer.cpp
+++ b/integer.cpp
@@ -318,7 +318,7 @@ public:
 #endif
 	{
 #if defined(CRYPTOPP_NATIVE_DWORD_AVAILABLE)
-#  if defined(IS_LITTLE_ENDIAN)
+#  if defined(CRYPTOPP_LITTLE_ENDIAN)
 		const word t[2] = {low,high};
 		memcpy(&m_whole, &t, sizeof(m_whole));
 #  else
@@ -423,7 +423,7 @@ private:
 	//   Thanks to Martin Bonner at http://stackoverflow.com/a/39507183
     struct half_words
     {
-    #ifdef IS_LITTLE_ENDIAN
+    #ifdef CRYPTOPP_LITTLE_ENDIAN
         word low;
         word high;
     #else
diff --git a/kalyna.cpp b/kalyna.cpp
index 356cf0ce..873bbd49 100644
--- a/kalyna.cpp
+++ b/kalyna.cpp
@@ -43,7 +43,7 @@ using CryptoPP::KalynaTab::IS;
 template <unsigned int NB>
 inline void MakeOddKey(const word64 evenkey[NB], word64 oddkey[NB])
 {
-#if defined(IS_BIG_ENDIAN)
+#if defined(CRYPTOPP_BIG_ENDIAN)
     if (NB == 2)
     {
         oddkey[0] = (evenkey[1] << 8) | (evenkey[0] >> 56);
diff --git a/misc.h b/misc.h
index 8c421c23..8d834899 100644
--- a/misc.h
+++ b/misc.h
@@ -1034,9 +1034,9 @@ inline bool IsAligned(const void *ptr)
 	return IsAlignedOn(ptr, GetAlignmentOf<T>());
 }
 
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 	typedef LittleEndian NativeByteOrder;
-#elif defined(IS_BIG_ENDIAN)
+#elif defined(CRYPTOPP_BIG_ENDIAN)
 	typedef BigEndian NativeByteOrder;
 #else
 # error "Unable to determine endian-ness"
@@ -1045,9 +1045,9 @@ inline bool IsAligned(const void *ptr)
 //! \brief Returns NativeByteOrder as an enumerated ByteOrder value
 //! \returns LittleEndian if the native byte order is little-endian, and BigEndian if the
 //!   native byte order is big-endian
-//! \details NativeByteOrder is a typedef depending on the platform. If IS_LITTLE_ENDIAN is
+//! \details NativeByteOrder is a typedef depending on the platform. If CRYPTOPP_LITTLE_ENDIAN is
 //!   set in config.h, then GetNativeByteOrder returns LittleEndian. If
-//!   IS_BIG_ENDIAN is set, then GetNativeByteOrder returns BigEndian.
+//!   CRYPTOPP_BIG_ENDIAN is set, then GetNativeByteOrder returns BigEndian.
 //! \note There are other byte orders besides little- and big-endian, and they include bi-endian
 //!   and PDP-endian. If a system is neither little-endian nor big-endian, then a compile time
 //!   error occurs.
diff --git a/ppc-crypto.h b/ppc-crypto.h
index d5fc7987..5bfd7dd1 100644
--- a/ppc-crypto.h
+++ b/ppc-crypto.h
@@ -56,9 +56,9 @@ typedef uint64x2_p8 VectorType;
 //! \since Crypto++ 6.0
 inline void ReverseByteArrayLE(byte src[16])
 {
-#if defined(CRYPTOPP_XLC_VERSION) && defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_XLC_VERSION) && defined(CRYPTOPP_LITTLE_ENDIAN)
 	vec_st(vec_reve(vec_ld(0, src)), 0, src);
-#elif defined(IS_LITTLE_ENDIAN)
+#elif defined(CRYPTOPP_LITTLE_ENDIAN)
 	const uint8x16_p8 mask = {15,14,13,12, 11,10,9,8, 7,6,5,4, 3,2,1,0};
 	const uint8x16_p8 zero = {0};
 	vec_vsx_st(vec_perm(vec_vsx_ld(0, src), zero, mask), 0, src);
@@ -91,7 +91,7 @@ inline VectorType VectorLoadBE(const uint8_t src[16])
 #if defined(CRYPTOPP_XLC_VERSION)
 	return (VectorType)vec_xl_be(0, (uint8_t*)src);
 #else
-# if defined(IS_LITTLE_ENDIAN)
+# if defined(CRYPTOPP_LITTLE_ENDIAN)
 	return (VectorType)Reverse(vec_vsx_ld(0, (uint8_t*)src));
 # else
 	return (VectorType)vec_vsx_ld(0, (uint8_t*)src);
@@ -112,7 +112,7 @@ inline VectorType VectorLoadBE(int off, const uint8_t src[16])
 #if defined(CRYPTOPP_XLC_VERSION)
 	return (VectorType)vec_xl_be(off, (uint8_t*)src);
 #else
-# if defined(IS_LITTLE_ENDIAN)
+# if defined(CRYPTOPP_LITTLE_ENDIAN)
 	return (VectorType)Reverse(vec_vsx_ld(off, (uint8_t*)src));
 # else
 	return (VectorType)vec_vsx_ld(off, (uint8_t*)src);
@@ -211,7 +211,7 @@ inline void VectorStoreBE(const T& src, uint8_t dest[16])
 #if defined(CRYPTOPP_XLC_VERSION)
 	vec_xst_be((uint8x16_p8)src, 0, (uint8_t*)dest);
 #else
-# if defined(IS_LITTLE_ENDIAN)
+# if defined(CRYPTOPP_LITTLE_ENDIAN)
 	vec_vsx_st(Reverse((uint8x16_p8)src), 0, (uint8_t*)dest);
 # else
 	vec_vsx_st((uint8x16_p8)src, 0, (uint8_t*)dest);
@@ -234,7 +234,7 @@ inline void VectorStoreBE(const T& src, int off, uint8_t dest[16])
 #if defined(CRYPTOPP_XLC_VERSION)
 	vec_xst_be((uint8x16_p8)src, off, (uint8_t*)dest);
 #else
-# if defined(IS_LITTLE_ENDIAN)
+# if defined(CRYPTOPP_LITTLE_ENDIAN)
 	vec_vsx_st(Reverse((uint8x16_p8)src), off, (uint8_t*)dest);
 # else
 	vec_vsx_st((uint8x16_p8)src, off, (uint8_t*)dest);
@@ -257,7 +257,7 @@ inline void VectorStore(const T& src, byte dest[16])
 #if defined(CRYPTOPP_XLC_VERSION)
 	vec_xst_be((uint8x16_p8)src, 0, (uint8_t*)dest);
 #else
-# if defined(IS_LITTLE_ENDIAN)
+# if defined(CRYPTOPP_LITTLE_ENDIAN)
 	vec_vsx_st(Reverse((uint8x16_p8)src), 0, (uint8_t*)dest);
 # else
 	vec_vsx_st((uint8x16_p8)src, 0, (uint8_t*)dest);
@@ -281,7 +281,7 @@ inline void VectorStore(const T& src, int off, byte dest[16])
 #if defined(CRYPTOPP_XLC_VERSION)
 	vec_xst_be((uint8x16_p8)src, off, (uint8_t*)dest);
 #else
-# if defined(IS_LITTLE_ENDIAN)
+# if defined(CRYPTOPP_LITTLE_ENDIAN)
 	vec_vsx_st(Reverse((uint8x16_p8)src), off, (uint8_t*)dest);
 # else
 	vec_vsx_st((uint8x16_p8)src, off, (uint8_t*)dest);
@@ -359,7 +359,7 @@ inline T1 VectorAdd(const T1& vec1, const T2& vec2)
 template <unsigned int C, class T1, class T2>
 inline T1 VectorShiftLeft(const T1& vec1, const T2& vec2)
 {
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 	return (T1)vec_sld((uint8x16_p8)vec2, (uint8x16_p8)vec1, 16-C);
 #else
 	return (T1)vec_sld((uint8x16_p8)vec1, (uint8x16_p8)vec2, C);
diff --git a/rijndael-simd.cpp b/rijndael-simd.cpp
index 8218bd79..810630d2 100644
--- a/rijndael-simd.cpp
+++ b/rijndael-simd.cpp
@@ -161,7 +161,7 @@ bool CPU_ProbeAES()
 
 ANONYMOUS_NAMESPACE_BEGIN
 
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 const word32 s_one[] = {0, 0, 0, 1<<24};  // uint32x4_t
 #else
 const word32 s_one[] = {0, 0, 0, 1};      // uint32x4_t
@@ -775,7 +775,7 @@ ANONYMOUS_NAMESPACE_BEGIN
 
 /* Round constants */
 static const uint32_t s_rcon[3][4] = {
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 	{0x01,0x01,0x01,0x01},   /*  1 */
 	{0x1b,0x1b,0x1b,0x1b},   /*  9 */
 	{0x36,0x36,0x36,0x36}    /* 10 */
@@ -788,7 +788,7 @@ static const uint32_t s_rcon[3][4] = {
 
 /* Permute mask */
 static const uint32_t s_mask[4] = {
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 	0x0c0f0e0d,0x0c0f0e0d,0x0c0f0e0d,0x0c0f0e0d
 #else
 	0x0d0e0f0c,0x0d0e0f0c,0x0d0e0f0c,0x0d0e0f0c
@@ -963,7 +963,7 @@ size_t Rijndael_AdvancedProcessBlocks_POWER8(F1 func1, F6 func6, const word32 *s
 	{
 		while (length >= 6*blockSize)
 		{
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 			const VectorType one = (VectorType)((uint64x2_p8){1,0});
 #else
 			const VectorType one = (VectorType)((uint64x2_p8){0,1});
@@ -1075,7 +1075,7 @@ void Rijndael_UncheckedSetKey_POWER8(const byte* userKey, size_t keyLen, word32*
 		uint8x16_p8 r4 = (uint8x16_p8)VectorLoadKey(s_rcon[0]);
 		uint8x16_p8 r5 = (uint8x16_p8)VectorLoadKey(s_mask);
 
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 		// Only the user key requires byte reversing.
 		// The subkeys are stored in proper endianess.
 		ReverseByteArrayLE(skptr);
@@ -1136,7 +1136,7 @@ void Rijndael_UncheckedSetKey_POWER8(const byte* userKey, size_t keyLen, word32*
 			rk += keyLen/4;
 		}
 
-#if defined(IS_LITTLE_ENDIAN)
+#if defined(CRYPTOPP_LITTLE_ENDIAN)
 		rk = rk_saved;
 		const uint8x16_p8 mask = ((uint8x16_p8){12,13,14,15, 8,9,10,11, 4,5,6,7, 0,1,2,3});
 		const uint8x16_p8 zero = {0};
diff --git a/rijndael.cpp b/rijndael.cpp
index 90663535..df551109 100644
--- a/rijndael.cpp
+++ b/rijndael.cpp
@@ -207,7 +207,7 @@ ANONYMOUS_NAMESPACE_END
 #define QUARTER_ROUND_E(t, a, b, c, d)		QUARTER_ROUND(TL_M, Te, t, a, b, c, d)
 #define QUARTER_ROUND_D(t, a, b, c, d)		QUARTER_ROUND(TL_M, Td, t, a, b, c, d)
 
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 	#define QUARTER_ROUND_FE(t, a, b, c, d)		QUARTER_ROUND(TL_F, Te, t, d, c, b, a)
 	#define QUARTER_ROUND_FD(t, a, b, c, d)		QUARTER_ROUND(TL_F, Td, t, d, c, b, a)
 	#if defined(CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS) || defined(CRYPTOPP_ALLOW_RIJNDAEL_UNALIGNED_DATA_ACCESS)
diff --git a/shark.cpp b/shark.cpp
index 0eb5eaeb..a8c304eb 100644
--- a/shark.cpp
+++ b/shark.cpp
@@ -67,7 +67,7 @@ void SHARK::Base::UncheckedSetKey(const byte *key, unsigned int keyLen, const Na
 			m_roundKeys[i] = SHARKTransform(m_roundKeys[i]);
 	}
 
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 	m_roundKeys[0] = ByteReverse(m_roundKeys[0]);
 	m_roundKeys[m_rounds] = ByteReverse(m_roundKeys[m_rounds]);
 #endif
@@ -84,7 +84,7 @@ void SHARK::Enc::InitForKeySetup()
 
 	m_roundKeys[DEFAULT_ROUNDS] = SHARKTransform(cbox[0][DEFAULT_ROUNDS]);
 
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 	m_roundKeys[0] = ByteReverse(m_roundKeys[0]);
 	m_roundKeys[m_rounds] = ByteReverse(m_roundKeys[m_rounds]);
 #endif
diff --git a/validat1.cpp b/validat1.cpp
index cd6dc837..9cdf71c2 100644
--- a/validat1.cpp
+++ b/validat1.cpp
@@ -226,7 +226,7 @@ bool TestSettings()
 
 	if (w == 0x04030201L)
 	{
-#ifdef IS_LITTLE_ENDIAN
+#ifdef CRYPTOPP_LITTLE_ENDIAN
 		std::cout << "passed:  ";
 #else
 		std::cout << "FAILED:  ";
@@ -236,7 +236,7 @@ bool TestSettings()
 	}
 	else if (w == 0x01020304L)
 	{
-#ifndef IS_LITTLE_ENDIAN
+#ifndef CRYPTOPP_LITTLE_ENDIAN
 		std::cout << "passed:  ";
 #else
 		std::cout << "FAILED:  ";