diff --git a/gcm.cpp b/gcm.cpp
index ba922844..9be90493 100644
--- a/gcm.cpp
+++ b/gcm.cpp
@@ -23,6 +23,10 @@
 // # undef CRYPTOPP_CLMUL_AVAILABLE
 // #endif
 
+// Clang casts
+#define M128I_CAST(x) ((__m128i *)(void *)(x))
+#define CONST_M128I_CAST(x) ((const __m128i *)(const void *)(x))
+
 #include "gcm.h"
 #include "cpu.h"
 
@@ -81,7 +85,7 @@ inline static void GCM_Xor16_SSE2(byte *a, const byte *b, const byte *c)
     CRYPTOPP_ASSERT(IsAlignedOn(a,GetAlignmentOf<__m128i>()));
     CRYPTOPP_ASSERT(IsAlignedOn(b,GetAlignmentOf<__m128i>()));
     CRYPTOPP_ASSERT(IsAlignedOn(c,GetAlignmentOf<__m128i>()));
-    *(__m128i *)(void *)a = _mm_xor_si128(*(__m128i *)(void *)b, *(__m128i *)(void *)c);
+    *M128I_CAST(a) = _mm_xor_si128(*M128I_CAST(b), *M128I_CAST(c));
 # else
     asm ("movdqa %1, %%xmm0; pxor %2, %%xmm0; movdqa %%xmm0, %0;" : "=m" (a[0]) : "m"(b[0]), "m"(c[0]));
 # endif
diff --git a/rijndael.cpp b/rijndael.cpp
index e04d323c..9a81cac1 100644
--- a/rijndael.cpp
+++ b/rijndael.cpp
@@ -92,6 +92,10 @@ NAMESPACE_BEGIN(CryptoPP)
 # define MAYBE_CONST const
 #endif
 
+// Clang casts
+#define M128I_CAST(x) ((__m128i *)(void *)(x))
+#define CONST_M128I_CAST(x) ((const __m128i *)(const void *)(x))
+
 #if defined(CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS) || defined(CRYPTOPP_ALLOW_RIJNDAEL_UNALIGNED_DATA_ACCESS)
 # if (CRYPTOPP_BOOL_SSE2_ASM_AVAILABLE || defined(CRYPTOPP_X64_MASM_AVAILABLE)) && !defined(CRYPTOPP_DISABLE_RIJNDAEL_ASM)
 namespace rdtable {CRYPTOPP_ALIGN_DATA(16) word64 Te[256+2];}