diff --git a/kernel/compat.h b/kernel/compat.h
index 46228080..4e3bb6bf 100644
--- a/kernel/compat.h
+++ b/kernel/compat.h
@@ -75,4 +75,9 @@ extern int _compat_unlink(
 #define HAS_BI_ERROR
 #endif
 
+/* adapt to 4e1b2d52a80d79296a5d899d73249748dea71a53 and many others */
+#ifdef bio_op
+#define HAS_NEW_BIO_OP
+#endif
+
 #endif /* _MARS_COMPAT */
diff --git a/kernel/mars_bio.c b/kernel/mars_bio.c
index 02f61ff8..8ea4e05a 100644
--- a/kernel/mars_bio.c
+++ b/kernel/mars_bio.c
@@ -41,14 +41,7 @@
 #include "lib_mapfree.h"
 
 #include "mars_bio.h"
-//      remove_this
 
-/* adapt to 4e1b2d52a80d79296a5d899d73249748dea71a53 and many others */
-#ifdef bio_op
-#define HAS_NEW_BIO_OP
-#endif
-
-//      end_remove_this
 int bio_nr_requests = 1024;
 
 static struct timing_stats timings[2] = {};