diff --git a/ppc-simd.h b/ppc-simd.h
index 2f96f756..880d15d4 100644
--- a/ppc-simd.h
+++ b/ppc-simd.h
@@ -372,7 +372,7 @@ template <class T1, class T2>
 inline T1 VectorEncrypt(const T1& state, const T2& key)
 {
 #if defined(CRYPTOPP_XLC_VERSION)
-    return (T1)__vcipher((uint64x2_p)state, (uint64x2_p)key);
+    return (T1)__vcipher((uint8x16_p)state, (uint8x16_p)key);
 #elif defined(CRYPTOPP_GCC_VERSION)
     return (T1)__builtin_crypto_vcipher((uint64x2_p)state, (uint64x2_p)key);
 #else
@@ -392,7 +392,7 @@ template <class T1, class T2>
 inline T1 VectorEncryptLast(const T1& state, const T2& key)
 {
 #if defined(CRYPTOPP_XLC_VERSION)
-    return (T1)__vcipherlast((uint64x2_p)state, (uint64x2_p)key);
+    return (T1)__vcipherlast((uint8x16_p)state, (uint8x16_p)key);
 #elif defined(CRYPTOPP_GCC_VERSION)
     return (T1)__builtin_crypto_vcipherlast((uint64x2_p)state, (uint64x2_p)key);
 #else
@@ -412,7 +412,7 @@ template <class T1, class T2>
 inline T1 VectorDecrypt(const T1& state, const T2& key)
 {
 #if defined(CRYPTOPP_XLC_VERSION)
-    return (T1)__vncipher((uint64x2_p)state, (uint64x2_p)key);
+    return (T1)__vncipher((uint8x16_p)state, (uint8x16_p)key);
 #elif defined(CRYPTOPP_GCC_VERSION)
     return (T1)__builtin_crypto_vncipher((uint64x2_p)state, (uint64x2_p)key);
 #else
@@ -432,7 +432,7 @@ template <class T1, class T2>
 inline T1 VectorDecryptLast(const T1& state, const T2& key)
 {
 #if defined(CRYPTOPP_XLC_VERSION)
-    return (T1)__vncipherlast((uint64x2_p)state, (uint64x2_p)key);
+    return (T1)__vncipherlast((uint8x16_p)state, (uint8x16_p)key);
 #elif defined(CRYPTOPP_GCC_VERSION)
     return (T1)__builtin_crypto_vncipherlast((uint64x2_p)state, (uint64x2_p)key);
 #else