diff --git a/pymake/utils/_usgs_src_update.py b/pymake/utils/_usgs_src_update.py
index 0bca9ac..6a6f666 100644
--- a/pymake/utils/_usgs_src_update.py
+++ b/pymake/utils/_usgs_src_update.py
@@ -887,6 +887,8 @@ def _update_mf6_external_dependencies(
         "Distributed/MpiRunControl.F90",
         "Distributed/MpiWorld.f90",
         "Solution/ParallelSolution.f90",
+        "Distributed/MpiUnitCache.f90",
+        "Distributed/MpiMessageCache.f90",
     )
     for file in parallel_files:
         path = srcdir / file
diff --git a/pymake/utils/usgsprograms.txt b/pymake/utils/usgsprograms.txt
index 4af573d..2ba0795 100644
--- a/pymake/utils/usgsprograms.txt
+++ b/pymake/utils/usgsprograms.txt
@@ -1,7 +1,7 @@
 target     ,  version,  current, url                                                                                            , dirname             , srcdir              ,    standard_switch, double_switch, shared_object
-mf6        ,  6.4.3  ,  True   , https://github.com/MODFLOW-USGS/modflow6/releases/download/6.4.3/mf6.4.3_linux.zip             , mf6.4.3_linux       , src                 ,    True           , False        , False
-zbud6      ,  6.4.3  ,  True   , https://github.com/MODFLOW-USGS/modflow6/releases/download/6.4.3/mf6.4.3_linux.zip             , mf6.4.3_linux       , utils/zonebudget/src,    True           , False        , False
-libmf6     ,  6.4.3  ,  True   , https://github.com/MODFLOW-USGS/modflow6/releases/download/6.4.3/mf6.4.3_linux.zip             , mf6.4.3_linux       , srcbmi              ,    True           , False        , True
+mf6        ,  6.4.4  ,  True   , https://github.com/MODFLOW-USGS/modflow6/releases/download/6.4.4/mf6.4.4_linux.zip             , mf6.4.4_linux       , src                 ,    True           , False        , False
+zbud6      ,  6.4.4  ,  True   , https://github.com/MODFLOW-USGS/modflow6/releases/download/6.4.4/mf6.4.4_linux.zip             , mf6.4.4_linux       , utils/zonebudget/src,    True           , False        , False
+libmf6     ,  6.4.4  ,  True   , https://github.com/MODFLOW-USGS/modflow6/releases/download/6.4.4/mf6.4.4_linux.zip             , mf6.4.4_linux       , srcbmi              ,    True           , False        , True
 mp7        ,  7.2.001,  True   , https://water.usgs.gov/water-resources/software/MODPATH/modpath_7_2_001.zip                    , modpath_7_2_001     , source              ,    True           , False        , False
 mt3dms     ,  5.3.0  ,  True   , https://github.com/MODFLOW-USGS/mt3dms/releases/download/2.0/mt3dms-2.0.zip                    , mt3dms-2.0          , true-binary         ,    True           , False        , False
 mt3dusgs   ,  1.1.0  ,  True   , https://water.usgs.gov/water-resources/software/MT3D-USGS/mt3dusgs1.1.0.zip                    , mt3dusgs1.1.0       , src                 ,    True           , False        , False