diff --git a/ip6/far_forward_fields_100.xml b/ip6/far_forward_fields_100.xml
index 1ce9dab2ef650387d76a05190f9a5321fe123ec7..cb7faa83b9e89fb7833ee7e3324863f8407c00c4 100644
--- a/ip6/far_forward_fields_100.xml
+++ b/ip6/far_forward_fields_100.xml
@@ -1,5 +1,7 @@
 <define>
 
+  <constant name="IonBeamEnergy" value="100*GeV" />
+
   <comment> 
       These are the values from Scott's tables for the 50cm shifted hadron FF 100 GeV proton lattice. Notice they mostly do not scale with beam energy in the staightforward way from the previous lattice.
   </comment>
diff --git a/ip6/far_forward_fields_275.xml b/ip6/far_forward_fields_275.xml
index 4ce7c41837d94320632f0cc8e1d326edc14f9eee..b3d6e9e68d16cebb7bfea4f752e57dc446474d2f 100644
--- a/ip6/far_forward_fields_275.xml
+++ b/ip6/far_forward_fields_275.xml
@@ -1,5 +1,7 @@
 <define>
 
+  <constant name="IonBeamEnergy" value="275*GeV" />
+
   <comment> 
       All magnet values are input by hand and represent the implementation in EICRoot used for the Yellow Report.
   </comment>
diff --git a/ip6/far_forward_fields_41.xml b/ip6/far_forward_fields_41.xml
index aa5a7f603f0191ac95805962d269bf66f2497e33..e5c30cc650df0944f652435fae99d0db30fa4537 100644
--- a/ip6/far_forward_fields_41.xml
+++ b/ip6/far_forward_fields_41.xml
@@ -1,5 +1,7 @@
 <define>
 
+  <constant name="IonBeamEnergy" value="41*GeV" />
+
   <comment> 
       These are the values from Scott's tables for the 50cm shifted hadron FF 41 GeV proton lattice. Notice they mostly do not scale with beam energy in the staightforward way from the previous lattice.
   </comment>