diff --git a/lib/Differentiator/VectorForwardModeVisitor.cpp b/lib/Differentiator/VectorForwardModeVisitor.cpp
index 7bce4dd4b..c471c517d 100644
--- a/lib/Differentiator/VectorForwardModeVisitor.cpp
+++ b/lib/Differentiator/VectorForwardModeVisitor.cpp
@@ -58,7 +58,7 @@ DerivativeAndOverload VectorForwardModeVisitor::DeriveVectorMode() {
   assert(m_DiffReq.Mode == DiffMode::vector_forward_mode);
 
   DiffParams args{};
-  for (auto dParam : m_DiffReq.DVI)
+  for (const auto& dParam : m_DiffReq.DVI)
     args.push_back(dParam.param);
 
   // Generate name for the derivative function.