diff --git a/cbackend.cpp b/cbackend.cpp
index bcd4aed2..ab414770 100644
--- a/cbackend.cpp
+++ b/cbackend.cpp
@@ -4399,11 +4399,7 @@ bool CWriter::visitBuiltinCall(llvm::CallInst &I, llvm::Intrinsic::ID ID,
     if (I.getParent()->getParent()->arg_empty())
       Out << "vararg_dummy_arg";
     else
-#if ISPC_LLVM_VERSION <= ISPC_LLVM_4_0
-      writeOperand(&*(--I.getParent()->getParent()->arg_end()));
-#else // LLVM 5.0+
-      writeOperand(&*(I.getParent()->getParent()->arg_end()-1));
-#endif
+      writeOperand(&*(std::prev(I.getParent()->getParent()->arg_end())));
     Out << ')';
     return true;
   case llvm::Intrinsic::vaend: