diff --git a/gtsam/nonlinear/Values-inl.h b/gtsam/nonlinear/Values-inl.h
index d0f8a47905..6829e859b6 100644
--- a/gtsam/nonlinear/Values-inl.h
+++ b/gtsam/nonlinear/Values-inl.h
@@ -338,19 +338,18 @@ namespace gtsam {
    }  // internal
 
    /* ************************************************************************* */
-   template<typename ValueType>
-   ValueType Values::at(Key j) const {
+   template <typename ValueType>
+   const ValueType Values::at(Key j) const {
      // Find the item
      KeyValueMap::const_iterator item = values_.find(j);
 
      // Throw exception if it does not exist
-     if(item == values_.end())
-       throw ValuesKeyDoesNotExist("at", j);
+     if (item == values_.end()) throw ValuesKeyDoesNotExist("at", j);
 
-    // Check the type and throw exception if incorrect
-    // h() split in two lines to avoid internal compiler error (MSVC2017)
-    auto h = internal::handle<ValueType>();
-    return h(j,item->second);
+     // Check the type and throw exception if incorrect
+     // h() split in two lines to avoid internal compiler error (MSVC2017)
+     auto h = internal::handle<ValueType>();
+     return h(j, item->second);
   }
 
   /* ************************************************************************* */
diff --git a/gtsam/nonlinear/Values.h b/gtsam/nonlinear/Values.h
index b49188b68d..120c8839c5 100644
--- a/gtsam/nonlinear/Values.h
+++ b/gtsam/nonlinear/Values.h
@@ -187,8 +187,8 @@ namespace gtsam {
      * Dynamic matrices/vectors can be retrieved as fixed-size, but not vice-versa.
      * @return The stored value
      */
-    template<typename ValueType>
-    ValueType at(Key j) const;
+    template <typename ValueType>
+    const ValueType at(Key j) const;
 
     /// version for double
     double atDouble(size_t key) const { return at<double>(key);}