diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 18c6d74d62ec2..3936af993db4d 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -81,8 +81,8 @@ const KNOWN_FEATURES: &'static [(&'static str, &'static str, Option<u32>, Status
     ("associated_types", "1.0.0", None, Accepted),
     ("visible_private_types", "1.0.0", None, Active),
     ("slicing_syntax", "1.0.0", None, Accepted),
-    ("box_syntax", "1.0.0", None, Active),
-    ("placement_in_syntax", "1.0.0", None, Active),
+    ("box_syntax", "1.0.0", Some(27779), Active),
+    ("placement_in_syntax", "1.0.0", Some(27779), Active),
     ("pushpop_unsafe", "1.2.0", None, Active),
     ("on_unimplemented", "1.0.0", None, Active),
     ("simd_ffi", "1.0.0", None, Active),