diff --git a/runtime/libia2/threads.c b/runtime/libia2/threads.c
index e0624c4e4..b4c174099 100644
--- a/runtime/libia2/threads.c
+++ b/runtime/libia2/threads.c
@@ -84,7 +84,7 @@ void *ia2_thread_begin(void *arg) {
         "mov sp, x10\n"
       : [result] "=r"(result)
       : [fn] "r"(fn), [data] "r"(&data), [new_sp_addr] "r"(new_sp_addr)
-      : "x10");
+      : "x0", "x10");
 #endif
 
   return result;