diff --git a/gtsam/base/OptionalJacobian.h b/gtsam/base/OptionalJacobian.h
index 82a5ae7f48..fbec2f1cd0 100644
--- a/gtsam/base/OptionalJacobian.h
+++ b/gtsam/base/OptionalJacobian.h
@@ -112,7 +112,7 @@ class OptionalJacobian {
   //  template <typename Derived, bool InnerPanel>
   //  OptionalJacobian(Eigen::Block<Derived,Rows,Cols,InnerPanel> block) : map_(NULL) { ?? }
 
-  /// Return true is allocated, false if default constructor was used
+  /// Return true if allocated, false if default constructor was used
   operator bool() const {
     return map_.data() != NULL;
   }
@@ -197,7 +197,7 @@ class OptionalJacobian<Eigen::Dynamic, Eigen::Dynamic> {
 
 #endif
 
-  /// Return true is allocated, false if default constructor was used
+  /// Return true if allocated, false if default constructor was used
   operator bool() const {
     return pointer_!=NULL;
   }