diff --git a/lib/xmet/thermo.py b/lib/xmet/thermo.py
index 540ad00..b5b8c27 100644
--- a/lib/xmet/thermo.py
+++ b/lib/xmet/thermo.py
@@ -8,18 +8,14 @@ def vapor_pressure(dewpoint: float) -> float:
     """
     Return the pressure of vapor in a parcel of a given dewpoint.
     """
-    return 6.11 * 10 ** (
-        (7.5 * dewpoint) / (237.3 * dewpoint)
-    )
+    return 6.11 * 10 ** ((7.5 * dewpoint) / (237.3 + dewpoint))
 
 def saturated_vapor_pressure(temp: float) -> float:
     """
     Return the pressure at which the vapor and condensation of a parcel of a
     given temperature are at equilibrium.
     """
-    return 6.11 * 10 ** (
-        (7.5 * temp) / (237.3 * temp)
-    )
+    return 6.11 * 10 ** ((7.5 * temp) / (237.3 + temp))
 
 def mixing_ratio(dewpoint: float, pressure: float) -> float:
     """