diff --git a/Eigen/Core b/Eigen/Core
index b2e973a8c..f2a1ad1d8 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -50,11 +50,12 @@ namespace Eigen {
 
 #include "src/Core/NumTraits.h"
 #include "src/Core/MathFunctions.h"
-#include "src/Core/PacketMath.h"
+#include "src/Core/DummyPacketMath.h"
+
 #if defined EIGEN_VECTORIZE_SSE
-#include "src/Core/PacketMath_SSE.h"
+#include "src/Core/arch/SSE/PacketMath.h"
 #elif defined EIGEN_VECTORIZE_ALTIVEC
-#include "src/Core/PacketMath_Altivec.h"
+#include "src/Core/arch/AltiVec/PacketMath.h"
 #endif
 
 #include "src/Core/Functors.h"
diff --git a/Eigen/src/Core/PacketMath.h b/Eigen/src/Core/DummyPacketMath.h
similarity index 95%
rename from Eigen/src/Core/PacketMath.h
rename to Eigen/src/Core/DummyPacketMath.h
index 267192482..b7d418a01 100644
--- a/Eigen/src/Core/PacketMath.h
+++ b/Eigen/src/Core/DummyPacketMath.h
@@ -22,12 +22,8 @@
 // License and a copy of the GNU General Public License along with
 // Eigen. If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef EIGEN_PACKET_MATH_H
-#define EIGEN_PACKET_MATH_H
-
-#ifndef EIGEN_CACHEFRIENDLY_PRODUCT_THRESHOLD
-#define EIGEN_CACHEFRIENDLY_PRODUCT_THRESHOLD 16
-#endif
+#ifndef EIGEN_DUMMY_PACKET_MATH_H
+#define EIGEN_DUMMY_PACKET_MATH_H
 
 // Default implementation for types not supported by the vectorization.
 // In practice these functions are provided to make easier the writting
@@ -76,5 +72,5 @@ template <typename Scalar> inline Scalar ei_preduxp(const Scalar* vecs) { return
 /** \internal \returns the sum of the elements of \a a*/
 template <typename Scalar> inline Scalar ei_predux(const Scalar& a) { return a; }
 
-#endif // EIGEN_PACKET_MATH_H
+#endif // EIGEN_DUMMY_PACKET_MATH_H
 
diff --git a/Eigen/src/Core/PacketMath_Altivec.h b/Eigen/src/Core/arch/AltiVec/PacketMath.h
similarity index 97%
rename from Eigen/src/Core/PacketMath_Altivec.h
rename to Eigen/src/Core/arch/AltiVec/PacketMath.h
index 4056c1ddb..aec4e9312 100644
--- a/Eigen/src/Core/PacketMath_Altivec.h
+++ b/Eigen/src/Core/arch/AltiVec/PacketMath.h
@@ -26,11 +26,9 @@
 #ifndef EIGEN_PACKET_MATH_ALTIVEC_H
 #define EIGEN_PACKET_MATH_ALTIVEC_H
 
-#ifndef EIGEN_VECTORIZE_ALTIVEC
-#error include PacketMath_Altivec without EIGEN_VECTORIZE_ALTIVEC
-#endif
-
+#ifndef EIGEN_CACHEFRIENDLY_PRODUCT_THRESHOLD
 #define EIGEN_CACHEFRIENDLY_PRODUCT_THRESHOLD 4
+#endif
 
 static const vector int   v0i   = vec_splat_u32(0);
 static const vector int   v16i_ = vec_splat_u32(-16);
@@ -108,4 +106,3 @@ inline int    ei_pfirst(const vector int    a)
 }
 
 #endif // EIGEN_PACKET_MATH_ALTIVEC_H
-
diff --git a/Eigen/src/Core/PacketMath_SSE.h b/Eigen/src/Core/arch/SSE/PacketMath.h
similarity index 98%
rename from Eigen/src/Core/PacketMath_SSE.h
rename to Eigen/src/Core/arch/SSE/PacketMath.h
index dd467f52a..ffd6aebeb 100644
--- a/Eigen/src/Core/PacketMath_SSE.h
+++ b/Eigen/src/Core/arch/SSE/PacketMath.h
@@ -25,8 +25,8 @@
 #ifndef EIGEN_PACKET_MATH_SSE_H
 #define EIGEN_PACKET_MATH_SSE_H
 
-#ifndef EIGEN_VECTORIZE_SSE
-#error include PacketMath_SSE without EIGEN_VECTORIZE_SSE
+#ifndef EIGEN_CACHEFRIENDLY_PRODUCT_THRESHOLD
+#define EIGEN_CACHEFRIENDLY_PRODUCT_THRESHOLD 16
 #endif
 
 template<> struct ei_packet_traits<float>  { typedef __m128  type; enum {size=4}; };