diff --git a/src/storm/storage/prism/ModuleRenaming.cpp b/src/storm/storage/prism/ModuleRenaming.cpp
index 0d31ff4bb..9ea9f1736 100644
--- a/src/storm/storage/prism/ModuleRenaming.cpp
+++ b/src/storm/storage/prism/ModuleRenaming.cpp
@@ -26,6 +26,7 @@ namespace storm {
                 }
             }
             stream << "]";
+            return stream;
         }
         
     } // namespace prism