diff --git a/src/storage/expressions/ToExprtkStringVisitor.cpp b/src/storage/expressions/ToExprtkStringVisitor.cpp
index 9a1aac389..f3a89b2c5 100644
--- a/src/storage/expressions/ToExprtkStringVisitor.cpp
+++ b/src/storage/expressions/ToExprtkStringVisitor.cpp
@@ -7,7 +7,8 @@ namespace storm {
         }
         
         std::string ToExprtkStringVisitor::toString(BaseExpression const* expression) {
-            stream = std::stringstream();
+            stream.str("");
+            stream.clear();
             expression->accept(*this);
             return std::move(stream.str());
         }