diff --git a/gtsam/nonlinear/LevenbergMarquardtOptimizer.cpp b/gtsam/nonlinear/LevenbergMarquardtOptimizer.cpp
index 2cde6768f..08961db86 100644
--- a/gtsam/nonlinear/LevenbergMarquardtOptimizer.cpp
+++ b/gtsam/nonlinear/LevenbergMarquardtOptimizer.cpp
@@ -244,7 +244,7 @@ void LevenbergMarquardtOptimizer::iterate() {
     try {
       delta = solve(dampedSystem, state_.values, params_);
       systemSolvedSuccessfully = true;
-    } catch (IndeterminantLinearSystemException& e) {
+    } catch (IndeterminantLinearSystemException) {
       systemSolvedSuccessfully = false;
     }
 
diff --git a/gtsam/slam/SmartFactorBase.h b/gtsam/slam/SmartFactorBase.h
index 93931549f..1235fc6fb 100644
--- a/gtsam/slam/SmartFactorBase.h
+++ b/gtsam/slam/SmartFactorBase.h
@@ -325,7 +325,7 @@ public:
       const Cameras& cameras, const Point3& point,
       const double lambda = 0.0) const {
 
-    int numKeys = this->keys_.size();
+    size_t numKeys = this->keys_.size();
     std::vector<KeyMatrix2D> Fblocks;
     double f = computeJacobians(Fblocks, E, PointCov, b, cameras, point,
         lambda);
@@ -352,7 +352,7 @@ public:
     Eigen::JacobiSVD<Matrix> svd(E, Eigen::ComputeFullU);
     Vector s = svd.singularValues();
     // Enull = zeros(2 * numKeys, 2 * numKeys - 3);
-    int numKeys = this->keys_.size();
+    size_t numKeys = this->keys_.size();
     Enull = svd.matrixU().block(0, 3, 2 * numKeys, 2 * numKeys - 3); // last 2m-3 columns
 
     return f;
diff --git a/gtsam/slam/SmartProjectionFactor.h b/gtsam/slam/SmartProjectionFactor.h
index 7c3719cd8..043528fea 100644
--- a/gtsam/slam/SmartProjectionFactor.h
+++ b/gtsam/slam/SmartProjectionFactor.h
@@ -262,7 +262,7 @@ public:
           try {
             Point2 reprojectionError(camera.project(point_) - zi);
             totalReprojError += reprojectionError.vector().norm();
-          } catch (CheiralityException& e) {
+          } catch (CheiralityException) {
             cheiralityException_ = true;
           }
           i += 1;
diff --git a/wrap/FileWriter.cpp b/wrap/FileWriter.cpp
index c5e64614e..3f5461078 100644
--- a/wrap/FileWriter.cpp
+++ b/wrap/FileWriter.cpp
@@ -28,7 +28,7 @@ void FileWriter::emit(bool add_header, bool force_overwrite) const {
   bool file_exists = true;
   try {
     existing_contents = file_contents(filename_.c_str(), add_header);
-  } catch (CantOpenFile& e) {
+  } catch (CantOpenFile) {
     file_exists = false;
   }