diff --git a/phino.cabal b/phino.cabal
--- a/phino.cabal
+++ b/phino.cabal
@@ -1,7 +1,7 @@
 cabal-version:      3.0
 
 name:               phino
-version:            0.0.0.26
+version:            0.0.0.27
 license:            MIT
 synopsis:           Command-Line Manipulator of 𝜑-Calculus Expressions
 description:        Please see the README on GitHub at <https://github.com/objectionary/phino#readme>
diff --git a/src/XMIR.hs b/src/XMIR.hs
--- a/src/XMIR.hs
+++ b/src/XMIR.hs
@@ -142,6 +142,9 @@
 formationBinding (BiTau (AtLabel label) expr) ctx = do
   (base, children) <- expression expr ctx
   pure (Just (object [("name", label), ("base", base)] children))
+formationBinding (BiTau AtPhi expr) ctx = do
+  (base, children) <- expression expr ctx
+  pure (Just (object [("name", "φ"), ("base", base)] children))
 formationBinding (BiTau AtRho _) _ = pure Nothing
 formationBinding (BiDelta bytes) _ = pure (Just (NodeContent (T.pack (prettyBytes bytes))))
 formationBinding (BiLambda func) _ = pure (Just (object [("name", "λ")] []))