diff --git a/gtsam/geometry/Rot3.h b/gtsam/geometry/Rot3.h
index 93810d436..d35fa52f4 100644
--- a/gtsam/geometry/Rot3.h
+++ b/gtsam/geometry/Rot3.h
@@ -87,6 +87,9 @@ namespace gtsam {
     /** constructor from a rotation matrix */
     Rot3(const Matrix3& R);
 
+    /** constructor from a rotation matrix */
+    Rot3(const Matrix& R);
+
     /** Constructor from a quaternion.  This can also be called using a plain
      * Vector, due to implicit conversion from Vector to Quaternion
      * @param q The quaternion
diff --git a/gtsam/geometry/Rot3M.cpp b/gtsam/geometry/Rot3M.cpp
index 9fffb0c2e..b4c79de3b 100644
--- a/gtsam/geometry/Rot3M.cpp
+++ b/gtsam/geometry/Rot3M.cpp
@@ -55,6 +55,13 @@ Rot3::Rot3(const Matrix3& R) {
   rot_ = R;
 }
 
+/* ************************************************************************* */
+Rot3::Rot3(const Matrix& R) {
+  if (R.rows()!=3 || R.cols()!=3)
+    throw invalid_argument("Rot3 constructor expects 3*3 matrix");
+  rot_ = R;
+}
+
 /* ************************************************************************* */
 Rot3::Rot3(const Quaternion& q) : rot_(q.toRotationMatrix()) {
 }
diff --git a/gtsam/geometry/Rot3Q.cpp b/gtsam/geometry/Rot3Q.cpp
index 81ea77fb7..52fb4f262 100644
--- a/gtsam/geometry/Rot3Q.cpp
+++ b/gtsam/geometry/Rot3Q.cpp
@@ -52,6 +52,10 @@ namespace gtsam {
   Rot3::Rot3(const Matrix3& R) :
       quaternion_(R) {}
 
+  /* ************************************************************************* */
+  Rot3::Rot3(const Matrix& R) :
+      quaternion_(Matrix3(R)) {}
+
   /* ************************************************************************* */
   Rot3::Rot3(const Quaternion& q) :
       quaternion_(q) {