diff --git a/firmware/analog_input.cpp b/firmware/analog_input.cpp
index c3dda05..e0bd8dc 100644
--- a/firmware/analog_input.cpp
+++ b/firmware/analog_input.cpp
@@ -17,7 +17,7 @@ ADCConversionGroup convGroup =
     ADC_CFGR1_CONT | ADC_CFGR1_RES_12BIT,                  // CFGR1
     ADC_TR(0, 0),       // TR
     ADC_SMPR_SMP_7P5,      // SMPR
-    ADC_CHSELR_CHSEL0 | ADC_CHSELR_CHSEL1 | ADC_CHSELR_CHSEL2
+    ADC_CHSELR_CHSEL0 | ADC_CHSELR_CHSEL2 | ADC_CHSELR_CHSEL3
 };
 
 static float AverageSamples(adcsample_t* buffer, size_t idx)
@@ -42,7 +42,7 @@ AnalogResult AnalogSample()
     return
     {
         .NernstVoltage = AverageSamples(adcBuffer, 0) * NERNST_INPUT_GAIN,
-        .VirtualGroundVoltage = AverageSamples(adcBuffer, 1),
-        .PumpCurrentVoltage = AverageSamples(adcBuffer, 2),
+        .PumpCurrentVoltage = AverageSamples(adcBuffer, 1),
+        .VirtualGroundVoltageInt = AverageSamples(adcBuffer, 2),
     };
 }
diff --git a/firmware/analog_input.h b/firmware/analog_input.h
index 7f25e61..784b556 100644
--- a/firmware/analog_input.h
+++ b/firmware/analog_input.h
@@ -3,8 +3,8 @@
 struct AnalogResult
 {
     float NernstVoltage;
-    float VirtualGroundVoltage;
     float PumpCurrentVoltage;
+    float VirtualGroundVoltageInt;
 };
 
 AnalogResult AnalogSample();
diff --git a/firmware/sampling.cpp b/firmware/sampling.cpp
index 21b455c..2745133 100644
--- a/firmware/sampling.cpp
+++ b/firmware/sampling.cpp
@@ -43,7 +43,7 @@ static void SamplingThread(void*)
         nernstAc = f_abs(r2_opposite_phase - r_2);
         nernstDc = (r2_opposite_phase + r_2) / 2;
 
-        pumpCurrentSenseVoltage = 0.8f * pumpCurrentSenseVoltage + 0.2f * (result.PumpCurrentVoltage - HALF_VCC);
+        pumpCurrentSenseVoltage = 0.8f * pumpCurrentSenseVoltage + 0.2f * (result.PumpCurrentVoltage - result.VirtualGroundVoltageInt);
 
         // Shift history over by one
         r_3 = r_2;