diff --git a/src/ModFile.cc b/src/ModFile.cc
index 77a071dcd0449e5594f45a1a69adebb3ac4f311d..ee3512c035e878eb8244472cce358ef0a5f3b7f4 100644
--- a/src/ModFile.cc
+++ b/src/ModFile.cc
@@ -524,7 +524,7 @@ ModFile::transformPass(bool nostrict, bool stochastic, bool compute_xrefs, const
         }
       else if (trend_component_model_table.isExistingTrendComponentModelName(vems->aux_model_name))
         {
-          max_lag = trend_component_model_table.getMaxLag(vems->aux_model_name);
+          max_lag = trend_component_model_table.getMaxLag(vems->aux_model_name) + 1;
           lhs = trend_component_model_table.getLhs(vems->aux_model_name);
         }
       else