diff --git a/src/evb/FP_kinematics.cpp b/src/evb/FP_kinematics.cpp
index 9a558c9..cdb0f5b 100644
--- a/src/evb/FP_kinematics.cpp
+++ b/src/evb/FP_kinematics.cpp
@@ -61,10 +61,10 @@ double Delta_Z(int ZT, int AT, int ZP, int AP, int ZE, int AE,
   B /= 10000; //convert to tesla
   angle *= DEGTORAD;
 
-  MT = MASS.FindMass(ZT, AT) - ZT*RESTMASS_ELECTRON*UTOMEV;
-  MP = MASS.FindMass(ZP, AP) - ZP*RESTMASS_ELECTRON*UTOMEV;
-  ME = MASS.FindMass(ZE, AE) - ZE*RESTMASS_ELECTRON*UTOMEV;
-  MR = MASS.FindMass(ZR, AR) - ZR*RESTMASS_ELECTRON*UTOMEV;
+  MT = MASS.FindMass(ZT, AT);
+  MP = MASS.FindMass(ZP, AP);
+  ME = MASS.FindMass(ZE, AE);
+  MR = MASS.FindMass(ZR, AR);
   
   if (MT*MP*ME*MR == 0) {
     std::cerr << "***WARNING: error loading one or more masses; returning 0\n";