diff --git a/meshmode/discretization/connection/face.py b/meshmode/discretization/connection/face.py
index a0d4e71e2fb4dd9443dfe08714cb274973375d92..f45a95c1b72fe742505c90535aa783c6ae5fb971 100644
--- a/meshmode/discretization/connection/face.py
+++ b/meshmode/discretization/connection/face.py
@@ -168,9 +168,9 @@ def make_face_restriction(discr, group_factory, boundary_tag,
 
     :arg boundary_tag: The boundary tag for which to create a face
         restriction. May be
-        :class:`meshmode.discretization.connection.FRESTR_INTERIOR_FACES`
+        :class:`FACE_RESTR_INTERIOR`
         to indicate interior faces, or
-        :class:`meshmode.discretization.connection.FRESTR_ALL_FACES`
+        :class:`FACE_RESTR_ALL`
         to make a discretization consisting of all (interior and
         boundary) faces.
 
@@ -199,7 +199,7 @@ def make_face_restriction(discr, group_factory, boundary_tag,
         boundary_tag = FACE_RESTR_INTERIOR
         from warnings import warn
         warn("passing *None* for boundary_tag is deprecated--pass "
-                "FRESTR_INTERIOR_FACES instead",
+                "FACE_RESTR_INTERIOR instead",
                 DeprecationWarning, stacklevel=2)
 
     logger.info("building face restriction: start")
@@ -223,7 +223,8 @@ def make_face_restriction(discr, group_factory, boundary_tag,
     bdry_mesh_groups = []
     connection_data = {}
 
-    btag_bit = discr.mesh.boundary_tag_bit(boundary_tag)
+    if boundary_tag not in [FACE_RESTR_ALL, FACE_RESTR_INTERIOR]:
+        btag_bit = discr.mesh.boundary_tag_bit(boundary_tag)
 
     for igrp, (grp, fagrp_map) in enumerate(
             zip(discr.groups, discr.mesh.facial_adjacency_groups)):
diff --git a/meshmode/mesh/__init__.py b/meshmode/mesh/__init__.py
index 95416568b8023d92fa2c0a688e88e82dcf6ef728..2625515c47c537cacd4b7c9a86d66ace1adc940e 100644
--- a/meshmode/mesh/__init__.py
+++ b/meshmode/mesh/__init__.py
@@ -632,6 +632,11 @@ class Mesh(Record):
         A mapping that maps boundary tag identifiers to their
         corresponding index.
 
+        .. note::
+
+            Elements of :attr:`boundary_tags` that do not cover any
+            part of the boundary will not be keys in this dictionary.
+
     .. attribute:: vertex_id_dtype
 
     .. attribute:: element_id_dtype
@@ -882,6 +887,12 @@ class Mesh(Record):
         return self._facial_adjacency_groups
 
     def boundary_tag_bit(self, boundary_tag):
+        if boundary_tag is BTAG_NONE:
+            return 0
+
+        if boundary_tag not in self.boundary_tags:
+            raise ValueError("boundary tag '%s' is not known" % boundary_tag)
+
         try:
             return 1 << self.btag_to_index[boundary_tag]
         except KeyError: