diff --git a/arduino/library-arduino.json b/arduino/library-arduino.json
index 13c8b886..781c750b 100644
--- a/arduino/library-arduino.json
+++ b/arduino/library-arduino.json
@@ -1,6 +1,6 @@
 {
   "name": "Embedded Template Library - Arduino",
-  "version": "20.37.0",
+  "version": "20.37.1",
   "authors": {
     "name": "John Wellbelove",
     "email": "john.wellbelove@etlcpp.com"
diff --git a/arduino/library-arduino.properties b/arduino/library-arduino.properties
index 54329e4c..27e2d4d2 100644
--- a/arduino/library-arduino.properties
+++ b/arduino/library-arduino.properties
@@ -1,5 +1,5 @@
 name=Embedded Template Library - Arduino
-version=20.37.0
+version=20.37.1
 author= John Wellbelove <john.wellbelove@etlcpp.com>
 maintainer=John Wellbelove <john.wellbelove@etlcpp.com>
 license=MIT
diff --git a/include/etl/delegate_observer.h b/include/etl/delegate_observer.h
new file mode 100644
index 00000000..e2225cf9
--- /dev/null
+++ b/include/etl/delegate_observer.h
@@ -0,0 +1,262 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2023 John Wellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef ETL_DELEGATE_OBSERVER_INCLUDED
+#define ETL_DELEGATE_OBSERVER_INCLUDED
+
+#include "algorithm.h"
+
+#include "platform.h"
+#include "delegate.h"
+#include "vector.h"
+#include "exception.h"
+#include "error_handler.h"
+#include "utility.h"
+
+namespace etl
+{
+  //***************************************************************************
+  ///\ingroup observer
+  /// The base class for delegate observer exceptions.
+  //***************************************************************************
+  class delegate_observer_exception : public exception
+  {
+  public:
+
+    delegate_observer_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
+      : exception(reason_, file_name_, line_number_)
+    {
+    }
+  };
+
+  //***************************************************************************
+  ///\ingroup observer
+  /// The exception thrown when the delegate observer list is full.
+  //***************************************************************************
+  class delegate_observer_list_full : public delegate_observer_exception
+  {
+  public:
+
+    delegate_observer_list_full(string_type file_name_, numeric_type line_number_)
+      : delegate_observer_exception(ETL_ERROR_TEXT("delegate_observable:full", ETL_DELEGATE_OBSERVER_FILE_ID"A"), file_name_, line_number_)
+    {
+    }
+  };
+
+  //*********************************************************************
+  /// The object that is being observed.
+  ///\tparam MAX_OBSERVERS The maximum number of observers that can be accommodated.
+  ///\ingroup observer
+  //*********************************************************************
+  template <typename TNotification, const size_t MAX_OBSERVERS>
+  class delegate_observable
+  {
+  public:
+    
+    typedef etl::delegate<void(TNotification)> observer_type;
+
+  private:
+
+    //***********************************
+    // Item stored in the observer list.
+    //***********************************
+    struct observer_item
+    {
+      observer_item(observer_type observer_)
+        : observer(observer_)
+        , enabled(true)
+      {
+      }
+
+      observer_type observer;
+      bool          enabled;
+    };
+
+    //***********************************
+    // How to compare an observer with an observer list item.
+    //***********************************
+    struct compare_observers
+    {
+      compare_observers(observer_type& observer_)
+        : observer(&observer_)
+      {
+      }
+
+      bool operator ()(const observer_item& item) const
+      {
+        return observer == item.observer;
+      }
+
+      observer_type observer;
+    };
+
+    typedef etl::vector<observer_item, MAX_OBSERVERS> Observer_List;
+
+  public:
+
+    typedef size_t        size_type;
+    typedef TNotification notification_type;
+
+    //*****************************************************************
+    /// Add an observer to the list.
+    /// If asserts or exceptions are enabled then an etl::observable_observer_list_full
+    /// is emitted if the observer list is already full.
+    ///\param observer A reference to the observer.
+    //*****************************************************************
+    void add_observer(observer_type& observer)
+    {
+		  // See if we already have it in our list.
+      typename Observer_List::iterator i_observer_item = find_observer(observer);
+
+		  // Not there?
+      if (i_observer_item == observer_list.end())
+      {
+        // Is there enough room?
+        ETL_ASSERT_OR_RETURN(!observer_list.full(), ETL_ERROR(etl::observer_list_full));
+
+        // Add it.
+        observer_list.push_back(observer_item(observer));
+      }
+    }
+
+    //*****************************************************************
+    /// Remove a particular observer from the list.
+    ///\param observer A reference to the observer.
+    ///\return <b>true</b> if the observer was removed, <b>false</b> if not.
+    //*****************************************************************
+    bool remove_observer(observer_type& observer)
+    {
+      // See if we have it in our list.
+      typename Observer_List::iterator i_observer_item = find_observer(observer);
+
+      // Found it?
+      if (i_observer_item != observer_list.end())
+      {
+        // Erase it.
+        observer_list.erase(i_observer_item);
+        return true;
+      }
+      else
+      {
+        return false;
+      }
+    }
+
+    //*****************************************************************
+    /// Enable an observer
+    ///\param observer A reference to the observer.
+    ///\param state    <b>true</b> to enable, <b>false</b> to disable. Default is enable.
+    //*****************************************************************
+    void enable_observer(observer_type& observer, bool state = true)
+    {
+      // See if we have it in our list.
+      typename Observer_List::iterator i_observer_item = find_observer(observer);
+
+      // Found it?
+      if (i_observer_item != observer_list.end())
+      {
+        i_observer_item->enabled = state;
+      }
+    }
+
+    //*****************************************************************
+    /// Disable an observer
+    //*****************************************************************
+    void disable_observer(observer_type& observer)
+    {
+      // See if we have it in our list.
+      typename Observer_List::iterator i_observer_item = find_observer(observer);
+
+      // Found it?
+      if (i_observer_item != observer_list.end())
+      {
+        i_observer_item->enabled = false;
+      }
+    }
+
+    //*****************************************************************
+    /// Clear all observers from the list.
+    //*****************************************************************
+    void clear_observers()
+    {
+      observer_list.clear();
+    }
+
+    //*****************************************************************
+    /// Returns the number of observers.
+    //*****************************************************************
+    size_type number_of_observers() const
+    {
+      return observer_list.size();
+    }
+
+    //*****************************************************************
+    /// Notify all of the observers, sending them the notification.
+    ///\tparam TNotification The notification type.
+    ///\param n The notification.
+    //*****************************************************************
+    void notify_observers(TNotification n)
+    {
+      typename Observer_List::iterator i_observer_item = observer_list.begin();
+
+      while (i_observer_item != observer_list.end())
+      {
+        if (i_observer_item->enabled)
+        {
+          i_observer_item->p_observer->notification(n);
+        }
+
+        ++i_observer_item;
+      }
+    }
+
+  protected:
+
+    ~observable()
+    {
+    }
+
+  private:
+
+    //*****************************************************************
+    /// Find an observer in the list.
+    /// Returns the end of the list if not found.
+    //*****************************************************************
+    typename Observer_List::iterator find_observer(observer_type& observer_)
+    {
+      return etl::find_if(observer_list.begin(), observer_list.end(), compare_observers(observer_));
+    }
+
+    /// The list of observers.
+    Observer_List observer_list;
+  };
+}
+
+#endif
diff --git a/include/etl/version.h b/include/etl/version.h
index 65798392..2b97460d 100644
--- a/include/etl/version.h
+++ b/include/etl/version.h
@@ -40,7 +40,7 @@ SOFTWARE.
 
 #define ETL_VERSION_MAJOR 20
 #define ETL_VERSION_MINOR 37
-#define ETL_VERSION_PATCH 0
+#define ETL_VERSION_PATCH 1
 
 #define ETL_VERSION       ETL_STRING(ETL_VERSION_MAJOR) "." ETL_STRING(ETL_VERSION_MINOR) "." ETL_STRING(ETL_VERSION_PATCH)
 #define ETL_VERSION_W     ETL_WIDE_STRING(ETL_VERSION_MAJOR) L"." ETL_WIDE_STRING(ETL_VERSION_MINOR) L"." ETL_WIDE_STRING(ETL_VERSION_PATCH)
diff --git a/library.json b/library.json
index 5babfa9c..a4f35ab5 100644
--- a/library.json
+++ b/library.json
@@ -1,6 +1,6 @@
 {
   "name": "Embedded Template Library",
-  "version": "20.37.0",
+  "version": "20.37.1",
   "authors": {
     "name": "John Wellbelove",
     "email": "john.wellbelove@etlcpp.com"
diff --git a/library.properties b/library.properties
index de9beedf..26a95a04 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=Embedded Template Library
-version=20.37.0
+version=20.37.1
 author= John Wellbelove <john.wellbelove@etlcpp.com>
 maintainer=John Wellbelove <john.wellbelove@etlcpp.com>
 license=MIT
diff --git a/support/Release notes.txt b/support/Release notes.txt
index d73c7e19..6468d04e 100644
--- a/support/Release notes.txt	
+++ b/support/Release notes.txt	
@@ -1,3 +1,7 @@
+===============================================================================
+20.37.1
+Fixed etl::optional arrow and dereference operators.
+
 ===============================================================================
 20.37.0
 #708 Fix missing class key with friend.
diff --git a/test/test_optional.cpp b/test/test_optional.cpp
index fd30ac5f..c1cf0a0c 100644
--- a/test/test_optional.cpp
+++ b/test/test_optional.cpp
@@ -539,10 +539,52 @@ namespace
     //*************************************************************************
     TEST(test_optional_pod_assign_bug_714)
     {
-      etl::optional<int> o = 42;
-      o = etl::nullopt;
+      etl::optional<int> opt = 42;
+      opt = etl::nullopt;
 
-      CHECK_EQUAL(false, o.has_value());
+      CHECK_EQUAL(false, opt.has_value());
+    }
+
+    //*************************************************************************   
+    TEST(test_dereference_operator_bug_730)
+    {
+      etl::optional<int> opt = 42;
+
+      CHECK_EQUAL(42, *opt);
+    }
+
+    //*************************************************************************
+    TEST(test_const_dereference_operator_bug_730)
+    {
+      const etl::optional<int> opt = 42;
+
+      CHECK_EQUAL(42, *opt);
+    }
+
+    //*************************************************************************   
+    TEST(test_arrow_operator_bug_730)
+    {
+      struct Object
+      {
+        int value;
+      };
+
+      etl::optional<Object> opt = Object{ 42 };
+
+      CHECK_EQUAL(42, opt->value);
+    }
+
+    //*************************************************************************   
+    TEST(test_const_arrow_operator_bug_730)
+    {
+      struct Object
+      {
+        int value;
+      };
+
+      const etl::optional<Object> opt = Object{ 42 };
+
+      CHECK_EQUAL(42, opt->value);
     }
   };
 }
diff --git a/test/vs2022/etl.vcxproj.filters b/test/vs2022/etl.vcxproj.filters
index 8ba2b15f..f3864279 100644
--- a/test/vs2022/etl.vcxproj.filters
+++ b/test/vs2022/etl.vcxproj.filters
@@ -3398,9 +3398,6 @@
     <ClCompile Include="..\test_result.cpp">
       <Filter>Tests\Containers</Filter>
     </ClCompile>
-    <ClCompile Include="..\test_expected.cpp">
-      <Filter>Tests\Containers</Filter>
-    </ClCompile>
     <ClCompile Include="..\sanity-check\expected.h.t.cpp">
       <Filter>Tests\Syntax Checks\Source</Filter>
     </ClCompile>
@@ -3416,6 +3413,9 @@
     <ClCompile Include="..\test_intrusive_links.cpp">
       <Filter>Tests\Containers</Filter>
     </ClCompile>
+    <ClCompile Include="..\test_expected.cpp">
+      <Filter>Tests\Misc</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\..\library.properties">
diff --git a/version.txt b/version.txt
index 75d012d0..830f0d3c 100644
--- a/version.txt
+++ b/version.txt
@@ -1 +1 @@
-20.37.0
+20.37.1