diff --git a/sensors/bmpBackend.py b/sensors/bmpBackend.py
index b5ba677..2d6c9b4 100644
--- a/sensors/bmpBackend.py
+++ b/sensors/bmpBackend.py
@@ -167,6 +167,7 @@ def readPressure(self):
       UP = 23843
       self._cal_AC6 = 23153
       self._cal_AC5 = 32757
+      self._cal_MB = -32767
       self._cal_MC = -8711
       self._cal_MD = 2868
       self._cal_B1 = 6190
@@ -191,7 +192,7 @@ def readPressure(self):
 
     # Pressure Calculations
     B6 = B5 - 4000
-    X1 = (self._cal_B2 * (B6 * B6) >> 12) >> 11
+    X1 = (self._cal_B2 * ((B6 * B6) >> 12)) >> 11
     X2 = (self._cal_AC2 * B6) >> 11
     X3 = X1 + X2
     B3 = (((self._cal_AC1 * 4 + X3) << self.mode) + 2) / 4
@@ -219,7 +220,7 @@ def readPressure(self):
 
     X1 = (p >> 8) * (p >> 8)
     X1 = (X1 * 3038) >> 16
-    X2 = (-7375 * p) >> 16
+    X2 = (-7357 * p) >> 16
     if (self.debug):
       print "DBG: p  = %d" % (p)
       print "DBG: X1 = %d" % (X1)