diff --git a/src/lib_klee_replay.rs b/src/lib_klee_replay.rs
index 2838d4381929648208fa2b635842f38616c23dbd..199f7adc95124e73b95fee8cf3da82049293fc63 100644
--- a/src/lib_klee_replay.rs
+++ b/src/lib_klee_replay.rs
@@ -10,7 +10,7 @@ pub fn klee_assume(_cond: bool) {}
 pub fn klee_make_symbolic<T>(t: &mut T) {
     // force LLVM to consider data to be mutated
     unsafe {
-        core::arch::asm!("bkpt #2", in(a1) t)
+        core::arch::asm!("bkpt #2", in(r1) t)
     }
     // unsafe {
     //     llvm_asm!("bkpt #0" : /* output */: /* input */ "r"(t): /* clobber */ : "volatile")