diff --git a/libtrellis/CMakeLists.txt b/libtrellis/CMakeLists.txt
index d34d2e9..f51c44f 100644
--- a/libtrellis/CMakeLists.txt
+++ b/libtrellis/CMakeLists.txt
@@ -62,7 +62,7 @@ if (BUILD_PYTHON)
     endwhile ()

     if (NOT Boost_PYTHON_FOUND)
-        foreach (PyVer 3 36 37 38)
+        foreach (PyVer 3 36 37 38 39)
             find_package(Boost QUIET COMPONENTS python${PyVer} ${boost_libs})
             if ("${Boost_LIBRARIES}" MATCHES ".*(python|PYTHON).*" )
                 set(Boost_PYTHON_FOUND TRUE)