diff --git a/internal_tests/pytests/grid_stat/test_grid_stat_wrapper.py b/internal_tests/pytests/grid_stat/test_grid_stat_wrapper.py
index 017731ed79..239991bd74 100644
--- a/internal_tests/pytests/grid_stat/test_grid_stat_wrapper.py
+++ b/internal_tests/pytests/grid_stat/test_grid_stat_wrapper.py
@@ -484,6 +484,9 @@ def test_handle_climo_file_variables(metplus_config, config_overrides,
         ({'GRID_STAT_CLIMO_MEAN_HOUR_INTERVAL': '12', },
          {'METPLUS_CLIMO_MEAN_DICT': 'climo_mean = {hour_interval = 12;}'}),
 
+        ({'GRID_STAT_CLIMO_MEAN_HOUR_INTERVAL': 'NA', },
+         {'METPLUS_CLIMO_MEAN_DICT': 'climo_mean = {hour_interval = NA;}'}),
+
         ({
              'GRID_STAT_CLIMO_MEAN_FILE_NAME': '/some/climo_mean/file.txt',
              'GRID_STAT_CLIMO_MEAN_FIELD': '{name="CLM_NAME"; level="(0,0,*,*)";}',