diff --git a/Processes/UrQMD/UrQMD.cc b/Processes/UrQMD/UrQMD.cc
index adee6aafc98b512b781f569976443b87efb7f140..293d0c478273c6ff1907fea27050a7b539981f97 100644
--- a/Processes/UrQMD/UrQMD.cc
+++ b/Processes/UrQMD/UrQMD.cc
@@ -93,7 +93,7 @@ corsika::process::EProcessReturn UrQMD::DoInteraction(SetupProjectile& projectil
   } else {
     inputs_.prspflg = 1;
     sys_.Ap = 1; // even for non-baryons this has to be set, see vanilla UrQMD.f
-    rsys_.bdist = nucrad_(sys_.Ap) + nucrad_(Atarget) + 2 * options_.CTParam[30 - 1];
+    rsys_.bdist = nucrad_(Atarget) + nucrad_(1) + 2 * options_.CTParam[30 - 1];
 
     auto const [ityp, iso3] = ConvertToUrQMD(projectileCode);
     // todo: conversion of K_long/short into strong eigenstates;