diff --git a/lib/xmet/thermo.py b/lib/xmet/thermo.py
index 6d1026c..e06a7b5 100644
--- a/lib/xmet/thermo.py
+++ b/lib/xmet/thermo.py
@@ -3,6 +3,7 @@ import math
 from typing import Callable
 
 from xmet.series import Series
+from xmet.units  import rad, kelvin, celsius
 
 LAPSE_RATE_DRY = 9.8 / 1000 # degrees C per km
 
@@ -11,12 +12,6 @@ PRESSURE_MSL  = 1013.25
 PRESSURE_MIN  =  100
 PRESSURE_STEP =   50
 
-def kelvin(c: float) -> float:
-    return 273.15 + c
-
-def celsius(k: float) -> float:
-    return k - 273.15
-
 def virtual_temp(temp: float, dewpoint: float, pressure: float) -> float:
     a = 7.5 * dewpoint
     b = 237.3 + dewpoint