diff --git a/QuantLib.vcxproj b/QuantLib.vcxproj
index 29b846cad23..a0bbb274750 100644
--- a/QuantLib.vcxproj
+++ b/QuantLib.vcxproj
@@ -2831,7 +2831,6 @@
     <ClCompile Include="ql\instrument.cpp" />
     <ClCompile Include="ql\interestrate.cpp" />
     <ClCompile Include="ql\money.cpp" />
-    <ClCompile Include="ql\optional.cpp" />
     <ClCompile Include="ql\position.cpp" />
     <ClCompile Include="ql\prices.cpp" />
     <ClCompile Include="ql\rebatedexercise.cpp" />
diff --git a/QuantLib.vcxproj.filters b/QuantLib.vcxproj.filters
index ab32dccb410..8b09bc52e18 100644
--- a/QuantLib.vcxproj.filters
+++ b/QuantLib.vcxproj.filters
@@ -6662,7 +6662,6 @@
     <ClCompile Include="ql\instrument.cpp" />
     <ClCompile Include="ql\interestrate.cpp" />
     <ClCompile Include="ql\money.cpp" />
-    <ClCompile Include="ql\optional.cpp" />
     <ClCompile Include="ql\position.cpp" />
     <ClCompile Include="ql\prices.cpp" />
     <ClCompile Include="ql\settings.cpp" />
diff --git a/ql/CMakeLists.txt b/ql/CMakeLists.txt
index 9c4896329c7..e000e1c276c 100644
--- a/ql/CMakeLists.txt
+++ b/ql/CMakeLists.txt
@@ -375,7 +375,7 @@ set(QL_SOURCES
     math/integrals/integral.cpp
     math/integrals/kronrodintegral.cpp
     math/integrals/segmentintegral.cpp
-    math/interpolations/chebyshevinterpolation.cpp    
+    math/interpolations/chebyshevinterpolation.cpp
     math/matrix.cpp
     math/matrixutilities/basisincompleteordered.cpp
     math/matrixutilities/bicgstab.cpp
@@ -646,7 +646,6 @@ set(QL_SOURCES
     models/volatility/constantestimator.cpp
     models/volatility/garch.cpp
     money.cpp
-    optional.cpp
     patterns/observable.cpp
     position.cpp
     prices.cpp
@@ -1451,7 +1450,7 @@ set(QL_HEADERS
     math/interpolations/backwardflatlinearinterpolation.hpp
     math/interpolations/bicubicsplineinterpolation.hpp
     math/interpolations/bilinearinterpolation.hpp
-    math/interpolations/chebyshevinterpolation.hpp    
+    math/interpolations/chebyshevinterpolation.hpp
     math/interpolations/convexmonotoneinterpolation.hpp
     math/interpolations/cubicinterpolation.hpp
     math/interpolations/extrapolation.hpp
diff --git a/ql/Makefile.am b/ql/Makefile.am
index 1d752a5ce7a..2236831b461 100644
--- a/ql/Makefile.am
+++ b/ql/Makefile.am
@@ -75,7 +75,6 @@ cpp_files = \
     instrument.cpp \
     interestrate.cpp \
     money.cpp \
-    optional.cpp \
     position.cpp \
     prices.cpp \
 	rebatedexercise.cpp \
@@ -103,7 +102,7 @@ else
 
 libQuantLib_la_SOURCES = $(cpp_files)
 
-EXTRA_DIST = 
+EXTRA_DIST =
 
 endif
 
@@ -180,4 +179,3 @@ install-data-hook:
 	rm .config.hpp
 depend:
 	makedepend $(INCLUDES) -- $(CFLAGS) -- $(SOURCES)
-
diff --git a/ql/optional.cpp b/ql/optional.cpp
deleted file mode 100644
index 5d762700c8e..00000000000
--- a/ql/optional.cpp
+++ /dev/null
@@ -1,29 +0,0 @@
-/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
-
-/*
- Copyright (C) 2023 Jonathan Sweemer
-
- This file is part of QuantLib, a free-software/open-source library
- for financial quantitative analysts and developers - http://quantlib.org/
-
- QuantLib is free software: you can redistribute it and/or modify it
- under the terms of the QuantLib license.  You should have received a
- copy of the license along with this program; if not, please email
- <quantlib-dev@lists.sf.net>. The license is also available online at
- <http://quantlib.org/license.shtml>.
-
- This program is distributed in the hope that it will be useful, but WITHOUT
- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- FOR A PARTICULAR PURPOSE.  See the license for more details.
-*/
-
-#include <ql/optional.hpp>
-
-namespace QuantLib::ext {
-
-        #if !defined(QL_USE_STD_OPTIONAL)
-        const boost::none_t& nullopt = boost::none;
-        #endif
-
-    }
-
diff --git a/ql/optional.hpp b/ql/optional.hpp
index e25d38f85cf..e9fe910e52b 100644
--- a/ql/optional.hpp
+++ b/ql/optional.hpp
@@ -36,12 +36,10 @@ namespace QuantLib::ext {
 
         #if defined(QL_USE_STD_OPTIONAL)
         using std::optional;                    // NOLINT(misc-unused-using-decls)
-        // here we can assume C++17
         inline constexpr const std::nullopt_t& nullopt = std::nullopt;
         #else
         using boost::optional;                  // NOLINT(misc-unused-using-decls)
-        // here we can't
-        extern const boost::none_t& nullopt;
+        inline constexpr const boost::none_t& nullopt = boost::none;
         #endif
 
     }