diff --git a/Eigen/src/Geometry/Rotation2D.h b/Eigen/src/Geometry/Rotation2D.h
index 65aa83be5..8b0ddcfb0 100644
--- a/Eigen/src/Geometry/Rotation2D.h
+++ b/Eigen/src/Geometry/Rotation2D.h
@@ -64,6 +64,16 @@ public:
   /** Default constructor wihtout initialization. The represented rotation is undefined. */
   Rotation2D() {}
 
+  /** Construct a 2D rotation from a 2x2 rotation matrix \a mat.
+    *
+    * \sa fromRotationMatrix()
+    */
+  template<typename Derived>
+  explicit Rotation2D(const MatrixBase<Derived>& m)
+  {
+    fromRotationMatrix(m.derived());
+  }
+
   /** \returns the rotation angle */
   inline Scalar angle() const { return m_angle; }
 
@@ -103,6 +113,17 @@ public:
   Rotation2D& fromRotationMatrix(const MatrixBase<Derived>& m);
   Matrix2 toRotationMatrix() const;
 
+  /** Set \c *this from a 2x2 rotation matrix \a mat.
+    * In other words, this function extract the rotation angle from the rotation matrix.
+    *
+    * This method is an alias for fromRotationMatrix()
+    *
+    * \sa fromRotationMatrix()
+    */
+  template<typename Derived>
+  Rotation2D& operator=(const  MatrixBase<Derived>& m)
+  { return fromRotationMatrix(m.derived()); }
+
   /** \returns the spherical interpolation between \c *this and \a other using
     * parameter \a t. It is in fact equivalent to a linear interpolation.
     */
diff --git a/test/geo_transformations.cpp b/test/geo_transformations.cpp
index 94ed155ef..51f90036d 100644
--- a/test/geo_transformations.cpp
+++ b/test/geo_transformations.cpp
@@ -430,6 +430,10 @@ template<typename Scalar, int Mode, int Options> void transformations()
     VERIFY( rot2.smallestAngle() >= -Scalar(EIGEN_PI) );
     VERIFY( rot2.smallestAngle() <=  Scalar(EIGEN_PI) );
     VERIFY_IS_APPROX( angleToVec(rot2.smallestAngle()), angleToVec(rot2.angle()) );
+
+    Matrix<Scalar,2,2> rot2_as_mat(rot2);
+    Rotation2D<Scalar> rot3(rot2_as_mat);
+    VERIFY_IS_APPROX( angleToVec(rot2.smallestAngle()),  angleToVec(rot3.angle()) );
   }
 
   s0 = internal::random<Scalar>(-100,100);