diff --git a/src/Lean/Meta/Tactic/Grind/Arith/Internalize.lean b/src/Lean/Meta/Tactic/Grind/Arith/Internalize.lean
index d7493178314f..96fac2547f80 100644
--- a/src/Lean/Meta/Tactic/Grind/Arith/Internalize.lean
+++ b/src/Lean/Meta/Tactic/Grind/Arith/Internalize.lean
@@ -14,20 +14,20 @@ def internalizeTerm (_e : Expr) (_a : Expr) (_k : Nat) : GoalM Unit := do
   -- TODO
   return ()
 
-def internalizeCnstr (e : Expr) (c : Cnstr Expr) : GoalM Unit := OffsetM.run do
+def internalizeCnstr (e : Expr) : GoalM Unit := do
+  let some c := isNatOffsetCnstr? e | return ()
   let c := { c with
     a := (← mkNode c.a)
     b := (← mkNode c.b)
   }
   trace[grind.offset.internalize] "{e} ↦ {c}"
-  modify fun s => { s with
+  modify' fun s => { s with
     cnstrs := s.cnstrs.insert { expr := e } c
   }
 
 end Offset
 
 def internalize (e : Expr) : GoalM Unit := do
-  if let some c := isNatOffsetCnstr? e then
-    Offset.internalizeCnstr e c
+  Offset.internalizeCnstr e
 
 end Lean.Meta.Grind.Arith
diff --git a/src/Lean/Meta/Tactic/Grind/Arith/Main.lean b/src/Lean/Meta/Tactic/Grind/Arith/Main.lean
index 7f008d4c9b4b..d46388c3ae0b 100644
--- a/src/Lean/Meta/Tactic/Grind/Arith/Main.lean
+++ b/src/Lean/Meta/Tactic/Grind/Arith/Main.lean
@@ -13,11 +13,11 @@ namespace Offset
 def isCnstr? (e : Expr) : GoalM (Option (Cnstr NodeId)) :=
   return (← get).arith.offset.cnstrs.find? { expr := e }
 
-def assertTrue (c : Cnstr NodeId) (p : Expr) : GoalM Unit := OffsetM.run do
+def assertTrue (c : Cnstr NodeId) (p : Expr) : GoalM Unit := do
   addEdge c.a c.b c.k (← mkOfEqTrue p)
 
-def assertFalse (c : Cnstr NodeId) (p : Expr) : GoalM Unit := OffsetM.run do
-  let p := mkOfNegEqFalse (← get).nodes c p
+def assertFalse (c : Cnstr NodeId) (p : Expr) : GoalM Unit := do
+  let p := mkOfNegEqFalse (← get').nodes c p
   let c := c.neg
   addEdge c.a c.b c.k p
 
diff --git a/src/Lean/Meta/Tactic/Grind/Arith/Offset.lean b/src/Lean/Meta/Tactic/Grind/Arith/Offset.lean
index 4a4e6f1bf9e1..95fec2f7edb3 100644
--- a/src/Lean/Meta/Tactic/Grind/Arith/Offset.lean
+++ b/src/Lean/Meta/Tactic/Grind/Arith/Offset.lean
@@ -30,20 +30,18 @@ The main advantage of this module over a full linear integer arithmetic procedur
 its ability to efficiently detect all implied equalities and inequalities.
 -/
 
-abbrev OffsetM := StateT State GoalM
+def get' : GoalM State := do
+  return (← get).arith.offset
 
-def OffsetM.run (x : OffsetM α) : GoalM α := do
-  let os ← modifyGet fun s => (s.arith.offset, { s with arith.offset := {} })
-  let (a, os') ← StateT.run x os
-  modify fun s => { s with arith.offset := os' }
-  return a
+@[inline] def modify' (f : State → State) : GoalM Unit := do
+  modify fun s => { s with arith.offset := f s.arith.offset }
 
-def mkNode (expr : Expr) : OffsetM NodeId := do
-  if let some nodeId := (← get).nodeMap.find? { expr } then
+def mkNode (expr : Expr) : GoalM NodeId := do
+  if let some nodeId := (← get').nodeMap.find? { expr } then
     return nodeId
-  let nodeId : NodeId := (← get).nodes.size
+  let nodeId : NodeId := (← get').nodes.size
   trace[grind.offset.internalize.term] "{expr} ↦ #{nodeId}"
-  modify fun s => { s with
+  modify' fun s => { s with
     nodes   := s.nodes.push expr
     nodeMap := s.nodeMap.insert { expr } nodeId
     sources := s.sources.push {}
@@ -52,62 +50,63 @@ def mkNode (expr : Expr) : OffsetM NodeId := do
   }
   return nodeId
 
-def isUnsat : OffsetM Bool :=
-  return (← get).unsat.isSome
+def isUnsat : GoalM Bool :=
+  return (← get').unsat.isSome
 
-private def getDist? (u v : NodeId) : OffsetM (Option Int) := do
-  return (← get).targets[u]!.find? v
+private def getDist? (u v : NodeId) : GoalM (Option Int) := do
+  return (← get').targets[u]!.find? v
 
-private def getProof? (u v : NodeId) : OffsetM (Option ProofInfo) := do
-  return (← get).proofs[u]!.find? v
+private def getProof? (u v : NodeId) : GoalM (Option ProofInfo) := do
+  return (← get').proofs[u]!.find? v
 
-partial def extractProof (u v : NodeId) : OffsetM Expr := do
+partial def extractProof (u v : NodeId) : GoalM Expr := do
   go (← getProof? u v).get!
 where
-  go (p : ProofInfo) : OffsetM Expr := do
+  go (p : ProofInfo) : GoalM Expr := do
     if u == p.w then
       return p.proof
     else
       let p' := (← getProof? u p.w).get!
-      go (mkTrans (← get).nodes p' p v)
+      go (mkTrans (← get').nodes p' p v)
 
-private def setUnsat (_u _v : NodeId) (_k : Int) (p : Expr) : OffsetM Unit := do
-  modify fun s => { s with
+private def setUnsat (u v : NodeId) (k : Int) (p : Expr) : GoalM Unit := do
+  trace[Meta.debug] "unsat #{u}-({k})->#{v}"
+  modify' fun s => { s with
     unsat := p -- TODO
   }
 
-private def setDist (u v : NodeId) (k : Int) : OffsetM Unit := do
+private def setDist (u v : NodeId) (k : Int) : GoalM Unit := do
   trace[grind.offset.dist] "{({ a := u, b := v, k : Cnstr NodeId})}"
-  modify fun s => { s with
+  modify' fun s => { s with
     targets := s.targets.modify u fun es => es.insert v k
     sources := s.sources.modify v fun es => es.insert u k
   }
 
-private def setProof (u v : NodeId) (p : ProofInfo) : OffsetM Unit := do
-  modify fun s => { s with
+private def setProof (u v : NodeId) (p : ProofInfo) : GoalM Unit := do
+  modify' fun s => { s with
     proofs := s.proofs.modify u fun es => es.insert v p
   }
 
 @[inline]
-private def forEachSourceOf (u : NodeId) (f : NodeId → Int → OffsetM Unit) : OffsetM Unit := do
-  (← get).sources[u]!.forM f
+private def forEachSourceOf (u : NodeId) (f : NodeId → Int → GoalM Unit) : GoalM Unit := do
+  (← get').sources[u]!.forM f
 
 @[inline]
-private def forEachTargetOf (u : NodeId) (f : NodeId → Int → OffsetM Unit) : OffsetM Unit := do
-  (← get).targets[u]!.forM f
+private def forEachTargetOf (u : NodeId) (f : NodeId → Int → GoalM Unit) : GoalM Unit := do
+  (← get').targets[u]!.forM f
 
-private def isShorter (u v : NodeId) (k : Int) : OffsetM Bool := do
+private def isShorter (u v : NodeId) (k : Int) : GoalM Bool := do
   if let some k' ← getDist? u v then
     return k < k'
   else
     return true
 
-private def updateIfShorter (u v : NodeId) (k : Int) (w : NodeId) : OffsetM Unit := do
+private def updateIfShorter (u v : NodeId) (k : Int) (w : NodeId) : GoalM Unit := do
   if (← isShorter u v k) then
     setDist u v k
     setProof u v (← getProof? w v).get!
 
-def addEdge (u : NodeId) (v : NodeId) (k : Int) (p : Expr) : OffsetM Unit := do
+def addEdge (u : NodeId) (v : NodeId) (k : Int) (p : Expr) : GoalM Unit := do
   if (← isUnsat) then return ()
   if let some k' ← getDist? v u then
     if k'+k < 0 then
@@ -118,7 +117,7 @@ def addEdge (u : NodeId) (v : NodeId) (k : Int) (p : Expr) : OffsetM Unit := do
     setProof u v { w := u, k, proof := p }
     update
 where
-  update : OffsetM Unit := do
+  update : GoalM Unit := do
     forEachTargetOf v fun j k₂ => do
       /- Check whether new path: `u -(k)-> v -(k₂)-> j` is shorter -/
       updateIfShorter u j (k+k₂) v
@@ -129,15 +128,15 @@ where
         /- Check whether new path: `i -(k₁)-> u -(k)-> v -(k₂) -> j` is shorter -/
         updateIfShorter i j (k₁+k+k₂) v
 
-def traceDists : OffsetM Unit := do
-  let s ← get
+def traceDists : GoalM Unit := do
+  let s ← get'
   for u in [:s.targets.size], es in s.targets.toArray do
     for (v, k) in es do
       trace[grind.offset.dist] "#{u} -({k})-> #{v}"
 
-def Cnstr.toExpr (c : Cnstr NodeId) : OffsetM Expr := do
-  let a := (← get).nodes[c.a]!
-  let b := (← get).nodes[c.b]!
+def Cnstr.toExpr (c : Cnstr NodeId) : GoalM Expr := do
+  let a := (← get').nodes[c.a]!
+  let b := (← get').nodes[c.b]!
   let mk := if c.le then mkNatLE else mkNatEq
   if c.k == 0 then
     return mk a b
@@ -146,8 +145,8 @@ def Cnstr.toExpr (c : Cnstr NodeId) : OffsetM Expr := do
   else
     return mk a (mkNatAdd b (Lean.toExpr c.k.toNat))
 
-def checkInvariants : GoalM Unit := OffsetM.run do
-  let s ← get
+def checkInvariants : GoalM Unit := do
+  let s ← get'
   for u in [:s.targets.size], es in s.targets.toArray do
     for (v, k) in es do
       let c : Cnstr NodeId := { a := u, b := v, k }