diff --git a/lib/compiler-singlepass/src/codegen_x64.rs b/lib/compiler-singlepass/src/codegen_x64.rs
index ab66664377..6b392e4972 100644
--- a/lib/compiler-singlepass/src/codegen_x64.rs
+++ b/lib/compiler-singlepass/src/codegen_x64.rs
@@ -1313,16 +1313,12 @@ impl<'a> FuncGen<'a> {
                     }
                     match *param {
                         Location::Imm64(_) => {
-                            // Dummy value slot to be filled with `mov`.
-                            self.assembler.emit_push(Size::S64, Location::GPR(GPR::RAX));
-
-                            // Use R9 as the temporary register here, since:
-                            // - It is a temporary register that is not used for any persistent value.
-                            // - This register as an argument location is only written to after `sort_call_movs`.'
+                            // Push R9 value slot to be exchange with `mov`.
+                            self.assembler.emit_push(Size::S64, Location::GPR(GPR::R9));
                             self.machine.reserve_unused_temp_gpr(GPR::R9);
                             self.assembler
                                 .emit_mov(Size::S64, *param, Location::GPR(GPR::R9));
-                            self.assembler.emit_mov(
+                            self.assembler.emit_xchg(
                                 Size::S64,
                                 Location::GPR(GPR::R9),
                                 Location::Memory(GPR::RSP, 0),