diff --git a/src/SubModel.cc b/src/SubModel.cc
index b6b764a19b4afca95f322c6a6f367891f25a1655..3b8233dd66df453a4b43b342af9e0103638e6189 100644
--- a/src/SubModel.cc
+++ b/src/SubModel.cc
@@ -943,6 +943,8 @@ VarExpectationModelTable::writeJsonOutput(ostream &output) const
 {
   for (const auto &name : names)
     {
+      if (name != *names.begin())
+        output << ", ";
       output << R"({"statementName": "var_expectation_model",)"
              << R"("model_name": ")" << name << R"(", )"
              << R"("expression": ")";