diff --git a/lib/xmet/thermo.py b/lib/xmet/thermo.py
index 1b9fd43..b15cc83 100644
--- a/lib/xmet/thermo.py
+++ b/lib/xmet/thermo.py
@@ -2,12 +2,12 @@ LAPSE_RATE_MOIST = 4.0 # degrees C per km
 LAPSE_RATE_DRY   = 9.8
 
 def vapor_pressure(dewpoint: float) -> float:
-    return 6.11 * 10 * (
+    return 6.11 * 10 ** (
         (7.5 * dewpoint) / (237.3 * dewpoint)
     )
 
 def saturated_vapor_pressure(temp: float) -> float:
-    return 6.11 * 10 * (
+    return 6.11 * 10 ** (
         (7.5 * temp) / (237.3 * temp)
     )