diff --git a/gtsam/geometry/Pose2.cpp b/gtsam/geometry/Pose2.cpp
index 96bdce69b..f54d6b034 100644
--- a/gtsam/geometry/Pose2.cpp
+++ b/gtsam/geometry/Pose2.cpp
@@ -365,7 +365,7 @@ boost::optional<Pose2> Pose2::Align(const Matrix& a, const Matrix& b) {
       "Pose2:Align expects 2*N matrices of equal shape.");
   }
   Point2Pairs ab_pairs;
-  for (size_t j=0; j < a.cols(); j++) {
+  for (size_t j=0; j < size_t(a.cols()); j++) {
     ab_pairs.emplace_back(a.col(j), b.col(j));
   }
   return Pose2::Align(ab_pairs);
diff --git a/gtsam/geometry/Pose3.cpp b/gtsam/geometry/Pose3.cpp
index b88d812a4..c79ff07c3 100644
--- a/gtsam/geometry/Pose3.cpp
+++ b/gtsam/geometry/Pose3.cpp
@@ -473,7 +473,7 @@ boost::optional<Pose3> Pose3::Align(const Matrix& a, const Matrix& b) {
       "Pose3:Align expects 3*N matrices of equal shape.");
   }
   Point3Pairs abPointPairs;
-  for (size_t j=0; j < a.cols(); j++) {
+  for (size_t j=0; j < size_t(a.cols()); j++) {
     abPointPairs.emplace_back(a.col(j), b.col(j));
   }
   return Pose3::Align(abPointPairs);