diff --git a/config.h b/config.h
index b5a6cfa7..96de92c6 100644
--- a/config.h
+++ b/config.h
@@ -574,9 +574,6 @@ NAMESPACE_END
 #  define CRYPTOPP_ARM_AES_AVAILABLE 1
 #  define CRYPTOPP_ARM_SHA_AVAILABLE 1
 #  define CRYPTOPP_ARM_CRYPTO_AVAILABLE 1
-#  if !defined(__apple_build_version__)
-#   define CRYPTOPP_ARM_PMULL_AVAILABLE 1
-#  endif
 # endif
 #endif
 
diff --git a/crc-simd.cpp b/crc-simd.cpp
index e1ed3ff0..439fd66c 100644
--- a/crc-simd.cpp
+++ b/crc-simd.cpp
@@ -29,6 +29,9 @@
 # include "nmmintrin.h"
 #endif
 
+// Don't include <arm_acle.h> when using Apple Clang. Early Apple compilers
+//  fail to compile with <arm_acle.h> included. Later Apple compilers compile
+//  intrinsics without <arm_acle.h> included.
 #if (CRYPTOPP_ARM_CRC32_AVAILABLE) && !defined(CRYPTOPP_APPLE_CLANG_VERSION)
 # include "arm_acle.h"
 #endif
diff --git a/gcm-simd.cpp b/gcm-simd.cpp
index bc230692..1033bb34 100644
--- a/gcm-simd.cpp
+++ b/gcm-simd.cpp
@@ -34,6 +34,9 @@
 # include "arm_neon.h"
 #endif
 
+// Don't include <arm_acle.h> when using Apple Clang. Early Apple compilers
+//  fail to compile with <arm_acle.h> included. Later Apple compilers compile
+//  intrinsics without <arm_acle.h> included.
 #if (CRYPTOPP_ARM_PMULL_AVAILABLE) && !defined(CRYPTOPP_APPLE_CLANG_VERSION)
 # include "arm_acle.h"
 #endif
diff --git a/rijndael-simd.cpp b/rijndael-simd.cpp
index 4f608ae7..58842576 100644
--- a/rijndael-simd.cpp
+++ b/rijndael-simd.cpp
@@ -46,6 +46,9 @@
 # include "arm_neon.h"
 #endif
 
+// Don't include <arm_acle.h> when using Apple Clang. Early Apple compilers
+//  fail to compile with <arm_acle.h> included. Later Apple compilers compile
+//  intrinsics without <arm_acle.h> included.
 #if (CRYPTOPP_ARM_AES_AVAILABLE) && !defined(CRYPTOPP_APPLE_CLANG_VERSION)
 # include "arm_acle.h"
 #endif
diff --git a/sha-simd.cpp b/sha-simd.cpp
index bb65a15b..ce319893 100644
--- a/sha-simd.cpp
+++ b/sha-simd.cpp
@@ -43,6 +43,9 @@
 # include "arm_neon.h"
 #endif
 
+// Don't include <arm_acle.h> when using Apple Clang. Early Apple compilers
+//  fail to compile with <arm_acle.h> included. Later Apple compilers compile
+//  intrinsics without <arm_acle.h> included.
 #if (CRYPTOPP_ARM_AES_AVAILABLE) && !defined(CRYPTOPP_APPLE_CLANG_VERSION)
 # include "arm_acle.h"
 #endif