diff --git a/sys/fs/tmpfs/tmpfs_subr.c b/sys/fs/tmpfs/tmpfs_subr.c
--- a/sys/fs/tmpfs/tmpfs_subr.c
+++ b/sys/fs/tmpfs/tmpfs_subr.c
@@ -443,7 +443,7 @@
 }
 
 SYSCTL_PROC(_vfs_tmpfs, OID_AUTO, memory_percent,
-    CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, &tmpfs_mem_percent, 0,
+    CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RWTUN, &tmpfs_mem_percent, 0,
     sysctl_mem_percent, "I",
     "Percent of available memory that can be used if no size limit");