diff --git a/include/clad/Differentiator/ErrorEstimator.h b/include/clad/Differentiator/ErrorEstimator.h
index 381fe42af..1a4bc3e89 100644
--- a/include/clad/Differentiator/ErrorEstimator.h
+++ b/include/clad/Differentiator/ErrorEstimator.h
@@ -48,7 +48,6 @@ class ErrorEstimationHandler : public ExternalRMVSource {
 
   std::stack<bool> m_ShouldEmit;
   ReverseModeVisitor* m_RMV;
-  llvm::SmallVectorImpl<clang::QualType>* m_ParamTypes = nullptr;
   llvm::SmallVectorImpl<clang::ParmVarDecl*>* m_Params = nullptr;
 
 public:
diff --git a/lib/Differentiator/ErrorEstimator.cpp b/lib/Differentiator/ErrorEstimator.cpp
index 368076483..9a1ae4adc 100644
--- a/lib/Differentiator/ErrorEstimator.cpp
+++ b/lib/Differentiator/ErrorEstimator.cpp
@@ -281,25 +281,23 @@ void ErrorEstimationHandler::ActBeforeCreatingDerivedFnParamTypes(
 
 void ErrorEstimationHandler::ActAfterCreatingDerivedFnParamTypes(
     llvm::SmallVectorImpl<QualType>& paramTypes) {
-  m_ParamTypes = &paramTypes;
   // If we are performing error estimation, our gradient function
   // will have an extra argument which will hold the final error value
-  paramTypes.push_back(
-      m_RMV->m_Context.getLValueReferenceType(m_RMV->m_Context.DoubleTy));
+  ASTContext& C = m_RMV->m_Context;
+  paramTypes.push_back(C.getLValueReferenceType(C.DoubleTy));
 }
 
 void ErrorEstimationHandler::ActAfterCreatingDerivedFnParams(
     llvm::SmallVectorImpl<ParmVarDecl*>& params) {
   m_Params = &params;
   // If in error estimation mode, create the error parameter
-  ASTContext& context = m_RMV->m_Context;
+  ASTContext& C = m_RMV->m_Context;
   // Repeat the above but for the error ouput var "_final_error"
+  QualType LastParamTy = C.getLValueReferenceType(C.DoubleTy);
   ParmVarDecl* errorVarDecl = ParmVarDecl::Create(
-      context, m_RMV->m_Derivative, noLoc, noLoc,
-      &context.Idents.get("_final_error"), m_ParamTypes->back(),
-      context.getTrivialTypeSourceInfo(m_ParamTypes->back(), noLoc),
-      params.front()->getStorageClass(),
-      /*DefArg=*/nullptr);
+      C, m_RMV->m_Derivative, noLoc, noLoc, &C.Idents.get("_final_error"),
+      LastParamTy, C.getTrivialTypeSourceInfo(LastParamTy, noLoc),
+      params.front()->getStorageClass(), /*DefArg=*/nullptr);
   params.push_back(errorVarDecl);
   m_RMV->m_Sema.PushOnScopeChains(params.back(), m_RMV->getCurrentScope(),
                                   /*AddToContext=*/false);