diff --git a/blake2.cpp b/blake2.cpp
index df2a709e..c696169e 100644
--- a/blake2.cpp
+++ b/blake2.cpp
@@ -14,7 +14,7 @@
 // Do so in both blake2.cpp and blake2-simd.cpp.
 // #undef CRYPTOPP_SSE41_AVAILABLE
 // #undef CRYPTOPP_ARM_NEON_AVAILABLE
-// #undef CRYPTOPP_POWER8_AVAILABLE
+// #undef CRYPTOPP_ALTIVEC_AVAILABLE
 
 // Disable NEON/ASIMD for Cortex-A53 and A57. The shifts are too slow and C/C++ is about
 // 3 cpb faster than NEON/ASIMD. Also see http://github.com/weidai11/cryptopp/issues/367.
@@ -22,9 +22,9 @@
 # undef CRYPTOPP_ARM_NEON_AVAILABLE
 #endif
 
-// Disable POWER7 on PowerPC big-endian machines. Blake2s/POWER7 runs slower than C++.
-#if defined(__powerpc__) && defined(__BIG_ENDIAN__)
+#if !(CRYPTOPP_ALTIVEC_AVAILABLE)
 # undef CRYPTOPP_POWER7_AVAILABLE
+# undef CRYPTOPP_POWER8_AVAILABLE
 #endif
 
 ANONYMOUS_NAMESPACE_BEGIN
diff --git a/blake2b-simd.cpp b/blake2b-simd.cpp
index 5a7f65d3..fa850e66 100644
--- a/blake2b-simd.cpp
+++ b/blake2b-simd.cpp
@@ -1,6 +1,6 @@
-
 // blake2-simd.cpp - written and placed in the public domain by
-//                   Jeffrey Walton, Uri Blumenthal and Marcel Raad.
+//                   Samuel Neves, Jeffrey Walton, Uri Blumenthal
+//                   and Marcel Raad.
 //
 //    This source file uses intrinsics to gain access to ARMv7a/ARMv8a
 //    NEON, Power8 and SSE4.1 instructions. A separate source file is
@@ -16,7 +16,7 @@
 // Do so in both blake2.cpp and blake2-simd.cpp.
 // #undef CRYPTOPP_SSE41_AVAILABLE
 // #undef CRYPTOPP_ARM_NEON_AVAILABLE
-// #undef CRYPTOPP_POWER8_AVAILABLE
+// #undef CRYPTOPP_ALTIVEC_AVAILABLE
 
 // Disable NEON/ASIMD for Cortex-A53 and A57. The shifts are too slow and C/C++ is about
 // 3 cpb faster than NEON/ASIMD. Also see http://github.com/weidai11/cryptopp/issues/367.
@@ -41,7 +41,7 @@
 # include <arm_acle.h>
 #endif
 
-#if defined(CRYPTOPP_POWER8_AVAILABLE)
+#if (CRYPTOPP_POWER8_AVAILABLE)
 # include "ppc-simd.h"
 #endif
 
diff --git a/blake2s-simd.cpp b/blake2s-simd.cpp
index 5db4caa2..fd1bc006 100644
--- a/blake2s-simd.cpp
+++ b/blake2s-simd.cpp
@@ -1,6 +1,6 @@
-
 // blake2-simd.cpp - written and placed in the public domain by
-//                   Jeffrey Walton, Uri Blumenthal and Marcel Raad.
+//                   Samuel Neves, Jeffrey Walton, Uri Blumenthal
+//                   and Marcel Raad.
 //
 //    This source file uses intrinsics to gain access to ARMv7a/ARMv8a
 //    NEON, Power7 and SSE4.1 instructions. A separate source file is
@@ -16,7 +16,7 @@
 // Do so in both blake2.cpp and blake2-simd.cpp.
 // #undef CRYPTOPP_SSE41_AVAILABLE
 // #undef CRYPTOPP_ARM_NEON_AVAILABLE
-// #undef CRYPTOPP_POWER7_AVAILABLE
+// #undef CRYPTOPP_ALTIVEC_AVAILABLE
 
 // Disable NEON/ASIMD for Cortex-A53 and A57. The shifts are too slow and C/C++ is about
 // 3 cpb faster than NEON/ASIMD. Also see http://github.com/weidai11/cryptopp/issues/367.
@@ -41,15 +41,10 @@
 # include <arm_acle.h>
 #endif
 
-#if defined(CRYPTOPP_POWER7_AVAILABLE)
+#if (CRYPTOPP_POWER7_AVAILABLE)
 # include "ppc-simd.h"
 #endif
 
-// Disable POWER7 on PowerPC big-endian machines. Blake2s/POWER7 runs slower than C++.
-#if defined(__powerpc__) && defined(__BIG_ENDIAN__)
-# undef CRYPTOPP_POWER7_AVAILABLE
-#endif
-
 ANONYMOUS_NAMESPACE_BEGIN
 
 using CryptoPP::word32;
diff --git a/ppc-simd.h b/ppc-simd.h
index 35abd507..2bbf35b7 100644
--- a/ppc-simd.h
+++ b/ppc-simd.h
@@ -27,8 +27,6 @@
 // We also need to handle the case of -DCRYPTOPP_ALTIVEC_AVAILABLE=0.
 #if !defined(__ALTIVEC__)
 # undef CRYPTOPP_ALTIVEC_AVAILABLE
-# undef CRYPTOPP_POWER7_AVAILABLE
-# undef CRYPTOPP_POWER8_AVAILABLE
 #endif
 
 #if !defined(_ARCH_PWR7)
@@ -49,8 +47,19 @@
 # undef bool
 #endif
 
+#if !(CRYPTOPP_ALTIVEC_AVAILABLE)
+# undef CRYPTOPP_POWER7_AVAILABLE
+# undef CRYPTOPP_POWER8_AVAILABLE
+# undef CRYPTOPP_POWER8_AES_AVAILABLE
+# undef CRYPTOPP_POWER8_VMULL_AVAILABLE
+# undef CRYPTOPP_POWER8_SHA_AVAILABLE
+#endif
+
 NAMESPACE_BEGIN(CryptoPP)
 
+// Wrap everything in this file based on CRYPTOPP_ALTIVEC_AVAILABLE
+#if (CRYPTOPP_ALTIVEC_AVAILABLE)
+
 // Datatypes
 #if (CRYPTOPP_ALTIVEC_AVAILABLE) || defined(CRYPTOPP_DOXYGEN_PROCESSING)
 typedef __vector unsigned char   uint8x16_p;
@@ -842,6 +851,8 @@ inline T VectorSHA512(const T& vec)
 
 #endif  // POWER8 crypto
 
+#endif  // CRYPTOPP_ALTIVEC_AVAILABLE
+
 NAMESPACE_END
 
 #endif  // CRYPTOPP_PPC_CRYPTO_H