diff --git a/gtsam/hybrid/HybridConditional.h b/gtsam/hybrid/HybridConditional.h
index be671d55f..e949fb865 100644
--- a/gtsam/hybrid/HybridConditional.h
+++ b/gtsam/hybrid/HybridConditional.h
@@ -173,7 +173,7 @@ class GTSAM_EXPORT HybridConditional
   }
 
   /// Get the type-erased pointer to the inner type
-  boost::shared_ptr<Factor> inner() { return inner_; }
+  boost::shared_ptr<Factor> inner() const { return inner_; }
 
   /// Return the error of the underlying conditional.
   /// Currently only implemented for Gaussian mixture.
diff --git a/gtsam/hybrid/HybridDiscreteFactor.h b/gtsam/hybrid/HybridDiscreteFactor.h
index 6e914d38b..7ac97443a 100644
--- a/gtsam/hybrid/HybridDiscreteFactor.h
+++ b/gtsam/hybrid/HybridDiscreteFactor.h
@@ -64,7 +64,7 @@ class GTSAM_EXPORT HybridDiscreteFactor : public HybridFactor {
   /// @name Standard Interface
   /// @{
 
-  /// Return pointer to the internal discrete factor
+  /// Return pointer to the internal discrete factor.
   DiscreteFactor::shared_ptr inner() const { return inner_; }
 
   /// Return the error of the underlying Discrete Factor.
diff --git a/gtsam/hybrid/HybridGaussianFactor.h b/gtsam/hybrid/HybridGaussianFactor.h
index 897da9caa..dc2f62857 100644
--- a/gtsam/hybrid/HybridGaussianFactor.h
+++ b/gtsam/hybrid/HybridGaussianFactor.h
@@ -96,7 +96,7 @@ class GTSAM_EXPORT HybridGaussianFactor : public HybridFactor {
   /// @name Standard Interface
   /// @{
 
-  /// Return pointer to the internal discrete factor
+  /// Return pointer to the internal Gaussian factor.
   GaussianFactor::shared_ptr inner() const { return inner_; }
 
   /// Return the error of the underlying Discrete Factor.
diff --git a/gtsam/hybrid/HybridNonlinearFactor.h b/gtsam/hybrid/HybridNonlinearFactor.h
index 9b3e780ef..56e30ba74 100644
--- a/gtsam/hybrid/HybridNonlinearFactor.h
+++ b/gtsam/hybrid/HybridNonlinearFactor.h
@@ -54,6 +54,7 @@ class HybridNonlinearFactor : public HybridFactor {
   /// @name Standard Interface
   /// @{
 
+  /// Return pointer to the internal nonlinear factor.
   NonlinearFactor::shared_ptr inner() const { return inner_; }
 
   /// Error for HybridValues is not provided for nonlinear factor.