diff --git a/tests/assembly/x86_64-windows-float-abi.rs b/tests/assembly/x86_64-windows-float-abi.rs
index e8900be1aae..cbc80910851 100644
--- a/tests/assembly/x86_64-windows-float-abi.rs
+++ b/tests/assembly/x86_64-windows-float-abi.rs
@@ -37,7 +37,8 @@ pub extern "C" fn second_f64(_: f64, x: f64) -> f64 {
 }
 
 // CHECK-LABEL: second_f128
-// CHECK: movaps %xmm1, %xmm0
+// FIXME(llvm21): this can be just %rdx instead of the regex once we don't test on LLVM 20
+// CHECK: movaps {{(%xmm1|\(%rdx\))}}, %xmm0
 // CHECK-NEXT: retq
 #[no_mangle]
 pub extern "C" fn second_f128(_: f128, x: f128) -> f128 {