diff --git a/src/DynamicModel.cc b/src/DynamicModel.cc
index 21624ba4..9e17b4c0 100644
--- a/src/DynamicModel.cc
+++ b/src/DynamicModel.cc
@@ -5616,7 +5616,7 @@ DynamicModel::writeJsonParamsDerivativesFile(ostream &output, bool writeDetails)
                  << R"(, "param2_col": )" << param2_col + 1;
 
       if (writeDetails)
-        gpp_output << R"(, "var": ")" << symbol_table.getName(var) << R"(")"
+        gpp_output << R"(, "var": ")" << symbol_table.getName(getSymbIDByDerivID(var)) << R"(")"
                    << R"(, "lag": )" << getLagByDerivID(var)
                    << R"(, "param1": ")" << symbol_table.getName(getSymbIDByDerivID(param1)) << R"(")"
                    << R"(, "param2": ")" << symbol_table.getName(getSymbIDByDerivID(param2)) << R"(")";
diff --git a/src/StaticModel.cc b/src/StaticModel.cc
index 3b8a78e3..639108e2 100644
--- a/src/StaticModel.cc
+++ b/src/StaticModel.cc
@@ -2061,7 +2061,7 @@ StaticModel::writeJsonParamsDerivativesFile(ostream &output, bool writeDetails)
                           << R"(, "param2_col": )" << param2_col;
 
       if (writeDetails)
-        third_derivs_output << R"(, "var": ")" << symbol_table.getName(var) << R"(")"
+        third_derivs_output << R"(, "var": ")" << symbol_table.getName(getSymbIDByDerivID(var)) << R"(")"
                             << R"(, "param1": ")" << symbol_table.getName(getSymbIDByDerivID(param1)) << R"(")"
                             << R"(, "param2": ")" << symbol_table.getName(getSymbIDByDerivID(param2)) << R"(")";