diff --git a/src/ModelTree.cc b/src/ModelTree.cc
index 4592db6a1830e0a6520a7c6c6225996f3d31e2fa..0c1c511c6cf66ddde71be919e4cb216660e30fdf 100644
--- a/src/ModelTree.cc
+++ b/src/ModelTree.cc
@@ -1591,7 +1591,7 @@ ModelTree::includeExcludeEquations(set<pair<string, string>> &eqs, bool exclude_
               excluded_vars.push_back(result.begin()->first);
             else
               {
-                cerr << "ERROR: Equation " << i
+                cerr << "ERROR: Equation " << i+1
                      << " has been excluded but does not have a single variable on LHS or `endogenous` tag" << endl;
                 exit(EXIT_FAILURE);
               }