diff --git a/ms5837.py b/ms5837.py
index 3074a3a..c0ea48e 100644
--- a/ms5837.py
+++ b/ms5837.py
@@ -116,8 +116,8 @@ def _calculate(self):
             OFF = self._C[2]*131072+(self._C[4]*dT)/64
             self._pressure = (self._D1*SENS/(2097152)-OFF)/(32768)
         else:
-            SENS = self._C[1]*32768+(C[3]*dT)/256
-            OFF = self._C[2]*65536+(C[4]*dT)/128
+            SENS = self._C[1]*32768+(self._C[3]*dT)/256
+            OFF = self._C[2]*65536+(self._C[4]*dT)/128
             self._pressure = (self._D1*SENS/(2097152)-OFF)/(8192)
             
         self._temperature = 2000+dT*self._C[6]/8388608