diff --git a/ohmpi.py b/ohmpi.py
index 6e2c0773ef49d90891e6e7eea02903989c00f19a..b5029eb8b2270d4879413451a6ff0e739fb54606 100644
--- a/ohmpi.py
+++ b/ohmpi.py
@@ -1029,7 +1029,7 @@ class OhmPi(object):
                             #     meas[k, 3] = AnalogIn(self.ads_voltage, ads.P0).voltage * 1000.
                             u0 = AnalogIn(self.ads_voltage, ads.P0).voltage * 1000.
                             u2 = AnalogIn(self.ads_voltage, ads.P2).voltage * 1000.
-                            u = np.max([u0, u2]) * (np.heaviside(u0 - u2, 1.) * 2 - 1.)
+                            u = np.max([u0, u2]) * (np.heaviside(u0 - u2, 1.) * 2 - 1.) - self.vmn_offset
                             meas[k, 1] = u
                             meas[k, 3] = u0
                             meas[k, 4] = u2 *-1.0
@@ -1072,7 +1072,7 @@ class OhmPi(object):
                             #     measpp[k, 4] = measpp[k, 1]
                             u0 = AnalogIn(self.ads_voltage, ads.P0).voltage * 1000.
                             u2 = AnalogIn(self.ads_voltage, ads.P2).voltage * 1000.
-                            u = np.max([u0, u2]) * (np.heaviside(u0 - u2, 1.) * 2 - 1.)
+                            u = np.max([u0, u2]) * (np.heaviside(u0 - u2, 1.) * 2 - 1.) - self.vmn_offset
                             measpp[k, 1] = u
                             measpp[k, 3] = u0
                             measpp[k, 4] = u2 * -1.0