diff --git a/gtsam_unstable/geometry/Similarity3.cpp b/gtsam_unstable/geometry/Similarity3.cpp
index 531a16428..9ea6ff80c 100644
--- a/gtsam_unstable/geometry/Similarity3.cpp
+++ b/gtsam_unstable/geometry/Similarity3.cpp
@@ -61,8 +61,8 @@ void Similarity3::print(const std::string& s) const {
 Similarity3 Similarity3::identity() {
   return Similarity3();
 }
-Similarity3 Similarity3::operator*(const Similarity3& T) const {
-  return Similarity3(R_ * T.R_, ((1.0 / T.s_) * t_) + R_ * T.t_, s_ * T.s_);
+Similarity3 Similarity3::operator*(const Similarity3& S) const {
+  return Similarity3(R_ * S.R_, ((1.0 / S.s_) * t_) + R_ * S.t_, s_ * S.s_);
 }
 
 Similarity3 Similarity3::inverse() const {
diff --git a/gtsam_unstable/geometry/Similarity3.h b/gtsam_unstable/geometry/Similarity3.h
index e04db4df7..a7797fbb4 100644
--- a/gtsam_unstable/geometry/Similarity3.h
+++ b/gtsam_unstable/geometry/Similarity3.h
@@ -88,7 +88,7 @@ public:
   GTSAM_UNSTABLE_EXPORT static Similarity3 identity();
 
   /// Composition
-  GTSAM_UNSTABLE_EXPORT Similarity3 operator*(const Similarity3& T) const;
+  GTSAM_UNSTABLE_EXPORT Similarity3 operator*(const Similarity3& S) const;
 
   /// Return the inverse
   GTSAM_UNSTABLE_EXPORT Similarity3 inverse() const;