diff --git a/lib/xmet/thermo.py b/lib/xmet/thermo.py
index 7cf2e4d..e96d02a 100644
--- a/lib/xmet/thermo.py
+++ b/lib/xmet/thermo.py
@@ -59,11 +59,11 @@ def lapse(temp: float, delta: float, rate=LAPSE_RATE_DRY) -> float:
 def moist_lapse_rate(temp: float, dewpoint: float, pressure: float) -> float:
     g   = 9.8076
     Hv  = 2501000
-    r   = mixing_ratio(dewpoint, pressure)
     Rsd = 287
     Rsw = 461.5
     Cpd = 1003.5
+    r   = saturated_mixing_ratio(dewpoint, pressure)
     T   = kelvin(temp)
 
     return g * (1 + (Hv * r) / (Rsd * T)) \
-             / (Cpd + ((Hv**2 * r) / (Rsw * T**2)))
+             / (Cpd + (((Hv**2) * r) / (Rsw * (T**2))))