diff --git a/metplus/util/constants.py b/metplus/util/constants.py
index 3b5c0f7ff..c080de2a6 100644
--- a/metplus/util/constants.py
+++ b/metplus/util/constants.py
@@ -25,6 +25,7 @@
     'mode': 'MODE',
     'mtd': 'MTD',
     'modetimedomain': 'MTD',
+    'pairstat': 'PairStat',
     'pb2nc': 'PB2NC',
     'pcpcombine': 'PCPCombine',
     'plotdataplane': 'PlotDataPlane',