diff --git a/src/EquationTags.cc b/src/EquationTags.cc
index 8fdac5a90f84a4d741e8193996c1784b06d53a9b..d60772122ae827ff14966b3f61fb0c69a92af3b0 100644
--- a/src/EquationTags.cc
+++ b/src/EquationTags.cc
@@ -123,6 +123,8 @@ EquationTags::writeOccbinOutput(ostream &output, const string &modstruct, bool j
       for (const auto & [key, value] : tags)
         output << modstruct << "occbin.constraint(" << idx << ")."
                << key << " = '" << value << "';" << endl;
+      output << modstruct << "occbin.constraint(" << idx << ").equation = "
+             << eqn+1 << ";" << endl;
     }
 }