diff --git a/lib/Differentiator/ReverseModeVisitor.cpp b/lib/Differentiator/ReverseModeVisitor.cpp
index ffdfea1b8..da7383e05 100644
--- a/lib/Differentiator/ReverseModeVisitor.cpp
+++ b/lib/Differentiator/ReverseModeVisitor.cpp
@@ -1652,7 +1652,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     }
 
     Expr* CUDAExecConfig = nullptr;
-    if (auto KCE = dyn_cast<CUDAKernelCallExpr>(CE))
+    if (const auto KCE = dyn_cast<CUDAKernelCallExpr>(CE))
       CUDAExecConfig = Clone(KCE->getConfig());
 
     // If the function is non_differentiable, return zero derivative.