diff --git a/eigen3.spec b/eigen3.spec
index fab74a7..12ffc0d 100644
--- a/eigen3.spec
+++ b/eigen3.spec
@@ -18,13 +18,17 @@
 
 Name:           eigen3
 Version:        3.3.9
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        A lightweight C++ template library for vector and matrix math
 
 License:        MPLv2.0 and LGPLv2+ and BSD
 URL:            http://eigen.tuxfamily.org/index.php?title=Main_Page
 Source0:        https://gitlab.com/libeigen/eigen/-/archive/%{version}/eigen-%{version}.tar.bz2
 
+# Backport fix for conflicting declarations of log1p
+# https://gitlab.com/libeigen/eigen/-/commit/d55d392e7b1136655b4223bea8e99cb2fe0a8afd.patch
+Patch0:         eigen3_logp.patch
+
 BuildRequires:  %{blaslib}-devel
 BuildRequires:  fftw-devel
 BuildRequires:  glew-devel
@@ -112,6 +116,9 @@ rm -f %{_vpath_builddir}/doc/html/unsupported/installdox
 
 
 %changelog
+* Tue Jan 19 2021 Sandro Mani <manisandro@gmail.com> - 3.3.9-2
+- Backport fix for conflicting declarations of log1p
+
 * Sun Dec 06 2020 Sandro Mani <manisandro@gmail.com> - 3.3.9-1
 - Update to 3.3.9
 
diff --git a/eigen3_logp.patch b/eigen3_logp.patch
new file mode 100644
index 0000000..5ebfa20
--- /dev/null
+++ b/eigen3_logp.patch
@@ -0,0 +1,27 @@
+diff -rupN --no-dereference eigen-3.3.9/Eigen/src/Core/MathFunctions.h eigen-3.3.9-new/Eigen/src/Core/MathFunctions.h
+--- eigen-3.3.9/Eigen/src/Core/MathFunctions.h	2020-12-04 22:53:41.000000000 +0100
++++ eigen-3.3.9-new/Eigen/src/Core/MathFunctions.h	2021-01-19 12:32:05.328624222 +0100
+@@ -485,12 +485,22 @@ struct log1p_impl {
+     EIGEN_STATIC_ASSERT_NON_INTEGER(Scalar)
+     #if EIGEN_HAS_CXX11_MATH
+     using std::log1p;
+-    #endif
++    #else
+     using std_fallback::log1p;
++    #endif
+     return log1p(x);
+   }
+ };
+ 
++// Specialization for complex types that are not supported by std::log1p.
++template <typename RealScalar>
++struct log1p_impl<std::complex<RealScalar> > {
++  EIGEN_DEVICE_FUNC static inline std::complex<RealScalar> run(
++      const std::complex<RealScalar>& x) {
++    EIGEN_STATIC_ASSERT_NON_INTEGER(RealScalar)
++    return std_fallback::log1p(x);
++  }
++};
+ 
+ template<typename Scalar>
+ struct log1p_retval