diff --git a/lib.h b/lib.h
index 3f358b3..0f0aac9 100644
--- a/lib.h
+++ b/lib.h
@@ -13,7 +13,9 @@ static
 void write(uint64_t fileno, void *buffer, size_t len) {
     uint64_t a,d;
     asm volatile("syscall"
-        :"=a"(a),"=d"(d):"a"(SYS_write),"D"(fileno),"S"(buffer),"d"(len):"memory");
+        :"=a"(a),"=d"(d)
+        :"a"(SYS_write),"D"(fileno),"S"(buffer),"d"(len)
+        :"cc","memory","%rcx","%r11");
 }
 
 [[noreturn]] static