diff --git a/CEP/DP3/DPPP_DDECal/src/Constraint.cc b/CEP/DP3/DPPP_DDECal/src/Constraint.cc
index 53f1abd41771ca143dbaf68ee994afc5b87d5716..aa0dcdbc6b416b41454f5c5613658fc040203942 100644
--- a/CEP/DP3/DPPP_DDECal/src/Constraint.cc
+++ b/CEP/DP3/DPPP_DDECal/src/Constraint.cc
@@ -91,7 +91,7 @@ std::vector<Constraint::Result> TECConstraint::Apply(
       _phaseFitters[thread].FitDataToTEC2Model(alpha, beta);
     }
 
-    res[0].vals[solutionIndex] = alpha / 8.44797245e9;
+    res[0].vals[solutionIndex] = alpha / -8.44797245e9;
     res[1].vals[solutionIndex] = beta;
     
     for(size_t ch=0; ch!=_nChannelBlocks; ++ch) {