diff --git a/include/private/gcconfig.h b/include/private/gcconfig.h
index 06ce9c736..8121457be 100644
--- a/include/private/gcconfig.h
+++ b/include/private/gcconfig.h
@@ -1083,7 +1083,7 @@ extern int etext[], _end[];
 #  define DATASTART PTR_ALIGN_UP((ptr_t)etext, 0x1000)
 #  define DATAEND ((ptr_t)_end)
 #  define DYNAMIC_LOADING
-#  define MPROTECT_VDB
+/* TODO: enable mprotect-based VDB */
 #  define USE_MMAP_ANON
 #endif /* SERENITY */
 
diff --git a/os_dep.c b/os_dep.c
index ee6da3efd..24af7934e 100644
--- a/os_dep.c
+++ b/os_dep.c
@@ -3259,8 +3259,7 @@ STATIC mach_port_t GC_task_self = 0;
 
 #  elif !defined(USE_WINALLOC)
 #    include <sys/mman.h>
-#    if !defined(AIX) && !defined(CYGWIN32) && !defined(HAIKU) \
-        && !defined(SERENITY)
+#    if !defined(AIX) && !defined(CYGWIN32) && !defined(HAIKU)
 #      include <sys/syscall.h>
 #    endif
 
@@ -3377,8 +3376,7 @@ is_header_found_async(const void *p)
 #      elif defined(IRIX5)
 #        define CODE_OK (si->si_code == EACCES)
 #      elif defined(AIX) || defined(COSMO) || defined(CYGWIN32) \
-          || defined(HAIKU) || defined(HURD) || defined(LINUX)  \
-          || defined(SERENITY)
+          || defined(HAIKU) || defined(HURD) || defined(LINUX)
 /* Linux: Empirically c.trapno == 14, on IA32, but is that useful?      */
 /* Should probably consider alignment issues on other architectures.    */
 #        define CODE_OK TRUE