diff --git a/test/main.h b/test/main.h
index e5f1a9ad5..bba5e7570 100644
--- a/test/main.h
+++ b/test/main.h
@@ -58,6 +58,10 @@
 #define isnan(X) please_protect_your_isnan_with_parentheses
 #define isinf(X) please_protect_your_isinf_with_parentheses
 #define isfinite(X) please_protect_your_isfinite_with_parentheses
+#ifdef M_PI
+#undef M_PI
+#endif
+#define M_PI please_use_EIGEN_PI_instead_of_M_PI
 
 #define FORBIDDEN_IDENTIFIER (this_identifier_is_forbidden_to_avoid_clashes) this_identifier_is_forbidden_to_avoid_clashes
 // B0 is defined in POSIX header termios.h
diff --git a/unsupported/Eigen/OpenGLSupport b/unsupported/Eigen/OpenGLSupport
index 288c6b0fb..87f50947d 100644
--- a/unsupported/Eigen/OpenGLSupport
+++ b/unsupported/Eigen/OpenGLSupport
@@ -180,11 +180,11 @@ template<typename Scalar> void glLoadMatrix(const Transform<Scalar,3,AffineCompa
 
 inline void glRotate(const Rotation2D<float>& rot)
 {
-  glRotatef(rot.angle()*180.f/float(M_PI), 0.f, 0.f, 1.f);
+  glRotatef(rot.angle()*180.f/float(EIGEN_PI), 0.f, 0.f, 1.f);
 }
 inline void glRotate(const Rotation2D<double>& rot)
 {
-  glRotated(rot.angle()*180.0/M_PI, 0.0, 0.0, 1.0);
+  glRotated(rot.angle()*180.0/EIGEN_PI, 0.0, 0.0, 1.0);
 }
 
 template<typename Derived> void glRotate(const RotationBase<Derived,3>& rot)
diff --git a/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h b/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h
index 463d7be0c..e43e86e90 100644
--- a/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h
+++ b/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h
@@ -11,10 +11,6 @@
 #ifndef EIGEN_MATRIX_LOGARITHM
 #define EIGEN_MATRIX_LOGARITHM
 
-#ifndef M_PI
-#define M_PI 3.141592653589793238462643383279503L
-#endif
-
 namespace Eigen { 
 
 namespace internal { 
@@ -65,8 +61,8 @@ void matrix_log_compute_2x2(const MatrixType& A, MatrixType& result)
   else
   {
     // computation in previous branch is inaccurate if A(1,1) \approx A(0,0)
-    int unwindingNumber = static_cast<int>(ceil((imag(logA11 - logA00) - M_PI) / (2*M_PI)));
-    result(0,1) = A(0,1) * (numext::log1p(y/A(0,0)) + Scalar(0,2*M_PI*unwindingNumber)) / y;
+    int unwindingNumber = static_cast<int>(ceil((imag(logA11 - logA00) - EIGEN_PI) / (2*EIGEN_PI)));
+    result(0,1) = A(0,1) * (numext::log1p(y/A(0,0)) + Scalar(0,2*EIGEN_PI*unwindingNumber)) / y;
   }
 }
 
diff --git a/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h b/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h
index 1e5a59c55..f37d31c3f 100644
--- a/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h
+++ b/unsupported/Eigen/src/MatrixFunctions/MatrixPower.h
@@ -298,8 +298,8 @@ MatrixPowerAtomic<MatrixType>::computeSuperDiag(const ComplexScalar& curr, const
 
   ComplexScalar logCurr = log(curr);
   ComplexScalar logPrev = log(prev);
-  int unwindingNumber = ceil((numext::imag(logCurr - logPrev) - M_PI) / (2*M_PI));
-  ComplexScalar w = numext::log1p((curr-prev)/prev)/RealScalar(2) + ComplexScalar(0, M_PI*unwindingNumber);
+  int unwindingNumber = ceil((numext::imag(logCurr - logPrev) - EIGEN_PI) / (2*EIGEN_PI));
+  ComplexScalar w = numext::log1p((curr-prev)/prev)/RealScalar(2) + ComplexScalar(0, EIGEN_PI*unwindingNumber);
   return RealScalar(2) * exp(RealScalar(0.5) * p * (logCurr + logPrev)) * sinh(p * w) / (curr - prev);
 }
 
diff --git a/unsupported/test/matrix_function.cpp b/unsupported/test/matrix_function.cpp
index 487d5a9b8..9a995f941 100644
--- a/unsupported/test/matrix_function.cpp
+++ b/unsupported/test/matrix_function.cpp
@@ -113,8 +113,8 @@ void testMatrixLogarithm(const MatrixType& A)
 
   MatrixType scaledA;
   RealScalar maxImagPartOfSpectrum = A.eigenvalues().imag().cwiseAbs().maxCoeff();
-  if (maxImagPartOfSpectrum >= 0.9 * M_PI)
-    scaledA = A * 0.9 * M_PI / maxImagPartOfSpectrum;
+  if (maxImagPartOfSpectrum >= 0.9 * EIGEN_PI)
+    scaledA = A * 0.9 * EIGEN_PI / maxImagPartOfSpectrum;
   else
     scaledA = A;
 
diff --git a/unsupported/test/matrix_power.cpp b/unsupported/test/matrix_power.cpp
index baf183d12..8e104ed1e 100644
--- a/unsupported/test/matrix_power.cpp
+++ b/unsupported/test/matrix_power.cpp
@@ -24,7 +24,7 @@ void test2dRotation(double tol)
     s = std::sin(angle);
     B << c, s, -s, c;
 
-    C = Apow(std::ldexp(angle,1) / M_PI);
+    C = Apow(std::ldexp(angle,1) / EIGEN_PI);
     std::cout << "test2dRotation: i = " << i << "   error powerm = " << relerr(C,B) << '\n';
     VERIFY(C.isApprox(B, tol));
   }