diff --git a/lib/Quox/Syntax/DimEq.idr b/lib/Quox/Syntax/DimEq.idr
index 9bb0cac..e8b9bdf 100644
--- a/lib/Quox/Syntax/DimEq.idr
+++ b/lib/Quox/Syntax/DimEq.idr
@@ -104,10 +104,10 @@ mutual
 
   export %inline
   setVar : (i, j : Var d) -> DimEq' d -> DimEq d
-  setVar i j eqs with (compareP i j)
-    _              | IsLT lt = setVar' i j lt eqs
-    setVar i i eqs | IsEQ    = C eqs
-    _              | IsGT gt = setVar' j i gt eqs
+  setVar i j eqs = case compareP i j of
+    IsLT lt => setVar' i j lt eqs
+    IsEQ    => C eqs
+    IsGT gt => setVar' j i gt eqs
 
 
 export %inline
diff --git a/lib/Quox/Typechecker.idr b/lib/Quox/Typechecker.idr
index cd57c76..fd17293 100644
--- a/lib/Quox/Typechecker.idr
+++ b/lib/Quox/Typechecker.idr
@@ -46,20 +46,23 @@ weakI : IsQty q => InferResult q d n -> InferResult q d (S n)
 weakI = {type $= weakT, qout $= (:< zero)}
 
 private
-lookupBound : IsQty q =>
-              {n : Nat} -> q -> Var n -> TyContext q d n -> InferResult q d n
-lookupBound pi VZ (MkTyContext {tctx = _ :< ty, _}) =
-  InfRes {type = weakT ty, qout = zero :< pi}
+lookupBound : IsQty q => q -> Var n -> TyContext q d n -> InferResult q d n
+lookupBound pi VZ ctx@(MkTyContext {tctx = _ :< ty, _}) =
+  InfRes {type = weakT ty, qout = zeroFor (tail ctx) :< pi}
 lookupBound pi (VS i) ctx =
   weakI $ lookupBound pi i (tail ctx)
 
 
 private %inline
 subjMult : IsQty q => (sg : SQty q) -> q -> SQty q
-subjMult (Element sg subj) qty =
-  if isYes (isZero sg) || isYes (isZero qty)
-     then Element zero zeroIsSubj
-     else Element sg   subj
+subjMult sg qty = if isYes $ isZero qty then szero else sg
+
+
+export
+makeDimEq : DContext d -> DimEq d
+makeDimEq DNil           = zeroEq
+makeDimEq (DBind dctx)   = makeDimEq dctx :<? Nothing
+makeDimEq (DEq p q dctx) = set p q $ makeDimEq dctx
 
 
 public export
@@ -78,23 +81,20 @@ parameters {auto _ : IsQty q} {auto _ : CanTC q m}
   -- computer but pushing is less work for the me
 
   export covering %inline
-  check : {d, n : Nat} ->
-          (ctx : TyContext q d n) -> (sg : SQty q) ->
+  check : (ctx : TyContext q d n) -> (sg : SQty q) ->
           (subj : Term q d n) -> (ty : Term q d n) ->
           m (CheckResult q n)
   check ctx sg subj ty = check' ctx sg (pushSubstsT subj) ty
 
   export covering %inline
-  infer : {d, n : Nat} ->
-          (ctx : TyContext q d n) -> (sg : SQty q) ->
+  infer : (ctx : TyContext q d n) -> (sg : SQty q) ->
           (subj : Elim q d n) ->
           m (InferResult q d n)
   infer ctx sg subj = infer' ctx sg (pushSubstsE subj)
 
 
   export covering
-  check' : {d, n : Nat} ->
-           (ctx : TyContext q d n) -> (sg : SQty q) ->
+  check' : (ctx : TyContext q d n) -> (sg : SQty q) ->
            (subj : NotCloTerm q d n) -> (ty : Term q d n) ->
            m (CheckResult q n)
 
@@ -102,7 +102,7 @@ parameters {auto _ : IsQty q} {auto _ : CanTC q m}
     l' <- expectTYPE ty
     expectEqualQ zero sg.fst
     unless (l < l') $ throwError $ BadUniverse l l'
-    pure zero
+    pure $ zeroFor ctx
 
   check' ctx sg (Element (Pi qty x arg res) _) ty = do
     l <- expectTYPE ty
@@ -113,7 +113,7 @@ parameters {auto _ : IsQty q} {auto _ : CanTC q m}
            ignore $ check (extendTy arg zero ctx) szero res (TYPE l)
          TUnused res =>
            ignore $ check ctx szero res (TYPE l)
-    pure zero
+    pure $ zeroFor ctx
 
   check' ctx sg (Element (Lam x body) _) ty = do
     (qty, arg, res) <- expectPi ty
@@ -125,19 +125,18 @@ parameters {auto _ : IsQty q} {auto _ : CanTC q m}
   check' ctx sg (Element (E e) _) ty = do
     infres <- infer ctx sg e
     ignore $ check ctx szero ty (TYPE UAny)
-    subT infres.type ty
+    subTWith (makeDimEq ctx.dctx) infres.type ty
     pure infres.qout
 
   export covering
-  infer' : {d, n : Nat} ->
-           (ctx : TyContext q d n) -> (sg : SQty q) ->
+  infer' : (ctx : TyContext q d n) -> (sg : SQty q) ->
            (subj : NotCloElim q d n) ->
            m (InferResult q d n)
 
   infer' ctx sg (Element (F x) _) = do
     Just g <- asks $ lookup x  | Nothing => throwError $ NotInScope x
     when (isZero g) $ expectEqualQ sg.fst zero
-    pure $ InfRes {type = g.type.get, qout = zero}
+    pure $ InfRes {type = g.type.get, qout = zeroFor ctx}
 
   infer' ctx sg (Element (B i) _) =
     pure $ lookupBound sg.fst i ctx
diff --git a/lib/Quox/Typing.idr b/lib/Quox/Typing.idr
index 899d815..d3f3450 100644
--- a/lib/Quox/Typing.idr
+++ b/lib/Quox/Typing.idr
@@ -81,6 +81,10 @@ namespace QOutput
     zero : {n : Nat} -> QOutput q n
     zero = pure zero
 
+    export
+    zeroFor : TyContext q _ n -> QOutput q n
+    zeroFor ctx = const zero <$> ctx.qctx
+
 
 public export
 CheckResult : Type -> Nat -> Type