diff --git a/src/Lean/CoreM.lean b/src/Lean/CoreM.lean
index 0e79af6a73..4e1d393c8c 100644
--- a/src/Lean/CoreM.lean
+++ b/src/Lean/CoreM.lean
@@ -40,7 +40,7 @@ def useDiagnosticMsg : MessageData :=
     if diagnostics.get ctx.opts then
       pure ""
     else
-      pure s!"\nAdditional diagnostic information may be available by using the `set_option {diagnostics.name} true` command."
+      pure s!"\nAdditional diagnostic information may be available using the `set_option {diagnostics.name} true` command."
 
 namespace Core
 
diff --git a/tests/lean/1007.lean.expected.out b/tests/lean/1007.lean.expected.out
index f947d152d2..fa277fe368 100644
--- a/tests/lean/1007.lean.expected.out
+++ b/tests/lean/1007.lean.expected.out
@@ -8,4 +8,4 @@
 1007.lean:39:4-39:7: warning: declaration uses 'sorry'
 1007.lean:56:64-56:78: error: failed to synthesize
   IsLin fun x => sum fun i => norm x
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/1102.lean.expected.out b/tests/lean/1102.lean.expected.out
index 127e652fdb..e9902f291b 100644
--- a/tests/lean/1102.lean.expected.out
+++ b/tests/lean/1102.lean.expected.out
@@ -1,3 +1,3 @@
 1102.lean:22:35-22:49: error: failed to synthesize
   DVR 1
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/2040.lean.expected.out b/tests/lean/2040.lean.expected.out
index 9788138631..8729afdea2 100644
--- a/tests/lean/2040.lean.expected.out
+++ b/tests/lean/2040.lean.expected.out
@@ -1,12 +1,12 @@
 2040.lean:8:8-8:13: error: failed to synthesize
   HPow Nat Nat Int
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 2040.lean:14:8-14:13: error: failed to synthesize
   HPow Nat Nat Int
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 2040.lean:20:8-20:13: error: failed to synthesize
   HPow Nat Nat Int
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 2040.lean:18:2-20:22: error: type mismatch
   trans (sorryAx (a = 37)) (sorryAx (37 = 2 ^ n))
 has type
diff --git a/tests/lean/2220.lean.expected.out b/tests/lean/2220.lean.expected.out
index 22390ad15f..012b465819 100644
--- a/tests/lean/2220.lean.expected.out
+++ b/tests/lean/2220.lean.expected.out
@@ -8,11 +8,11 @@
 @HPow.hPow Int Nat Int Int.instHPowNat (@OfNat.ofNat Int 3 (@instOfNat 3)) (@OfNat.ofNat Nat 2 (instOfNatNat 2)) : Int
 2220.lean:25:19-25:24: error: failed to synthesize
   HPow Nat Nat Int
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 @HAdd.hAdd Int Int Int (@instHAdd Int Int.instAdd) (@OfNat.ofNat Int 1 (@instOfNat 1))
   (@HPow.hPow Nat Nat Int ?m (@OfNat.ofNat Nat 3 (instOfNatNat 3)) (@OfNat.ofNat Nat 2 (instOfNatNat 2))) : Int
 2220.lean:26:12-26:17: error: failed to synthesize
   HPow Nat Nat Int
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 @HAdd.hAdd Int Int Int (@instHAdd Int Int.instAdd) (@OfNat.ofNat Int 1 (@instOfNat 1))
   (@HPow.hPow Nat Nat Int ?m (@OfNat.ofNat Nat 3 (instOfNatNat 3)) (@OfNat.ofNat Nat 2 (instOfNatNat 2))) : Int
diff --git a/tests/lean/2273.lean.expected.out b/tests/lean/2273.lean.expected.out
index dcc0ceb92c..9468bf4cc9 100644
--- a/tests/lean/2273.lean.expected.out
+++ b/tests/lean/2273.lean.expected.out
@@ -1,3 +1,3 @@
 2273.lean:9:8-9:14: error: failed to synthesize
   P 37
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/297.lean.expected.out b/tests/lean/297.lean.expected.out
index d7ca31788d..6642b1ddb1 100644
--- a/tests/lean/297.lean.expected.out
+++ b/tests/lean/297.lean.expected.out
@@ -3,4 +3,4 @@
 numerals are polymorphic in Lean, but the numeral `0` cannot be used in a context where the expected type is
   Sort ?u
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/386.lean.expected.out b/tests/lean/386.lean.expected.out
index 530fa5ba18..321c7108d3 100644
--- a/tests/lean/386.lean.expected.out
+++ b/tests/lean/386.lean.expected.out
@@ -1,3 +1,3 @@
 386.lean:9:2-9:46: error: failed to synthesize
   Fintype ?m
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/448.lean.expected.out b/tests/lean/448.lean.expected.out
index ec80bfed69..e9f6d96501 100644
--- a/tests/lean/448.lean.expected.out
+++ b/tests/lean/448.lean.expected.out
@@ -1,3 +1,3 @@
 448.lean:21:2-23:20: error: failed to synthesize
   MonadExceptOf IO.Error M
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/attrCmd.lean.expected.out b/tests/lean/attrCmd.lean.expected.out
index 5551509eae..37bca849b6 100644
--- a/tests/lean/attrCmd.lean.expected.out
+++ b/tests/lean/attrCmd.lean.expected.out
@@ -1,3 +1,3 @@
 attrCmd.lean:6:0-6:6: error: failed to synthesize
   Pure M
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/calcErrors.lean.expected.out b/tests/lean/calcErrors.lean.expected.out
index 85598c69c5..51cbc91626 100644
--- a/tests/lean/calcErrors.lean.expected.out
+++ b/tests/lean/calcErrors.lean.expected.out
@@ -12,7 +12,7 @@ calcErrors.lean:24:8-24:11: error: invalid 'calc' step, relation expected
   p a
 calcErrors.lean:31:8-31:13: error: invalid 'calc' step, failed to synthesize `Trans` instance
   Trans p p ?m
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 calcErrors.lean:41:7-41:12: error: invalid 'calc' step, left-hand-side is
   γ : Sort u_1
 previous right-hand-side is
diff --git a/tests/lean/defInst.lean.expected.out b/tests/lean/defInst.lean.expected.out
index 4014c89f3d..cf1ab9fccc 100644
--- a/tests/lean/defInst.lean.expected.out
+++ b/tests/lean/defInst.lean.expected.out
@@ -1,7 +1,7 @@
 [4, 5, 6]
 defInst.lean:8:26-8:32: error: failed to synthesize
   BEq Foo
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 fun x y => sorryAx (?m x y) true : (x y : Foo) → ?m x y
 [4, 5, 6]
 fun x y => x == y : Foo → Foo → Bool
diff --git a/tests/lean/defaultInstance.lean.expected.out b/tests/lean/defaultInstance.lean.expected.out
index ce40f49119..11d9930097 100644
--- a/tests/lean/defaultInstance.lean.expected.out
+++ b/tests/lean/defaultInstance.lean.expected.out
@@ -1,5 +1,5 @@
 defaultInstance.lean:20:20-20:23: error: failed to synthesize
   Foo Bool (?m x)
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 defaultInstance.lean:22:35-22:38: error: typeclass instance problem is stuck, it is often due to metavariables
   Foo Bool (?m x)
diff --git a/tests/lean/eagerUnfoldingIssue.lean.expected.out b/tests/lean/eagerUnfoldingIssue.lean.expected.out
index 098500b40a..cab207bb69 100644
--- a/tests/lean/eagerUnfoldingIssue.lean.expected.out
+++ b/tests/lean/eagerUnfoldingIssue.lean.expected.out
@@ -1,6 +1,6 @@
 eagerUnfoldingIssue.lean:6:2-6:17: error: failed to synthesize
   MonadLog (StateM Nat)
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 eagerUnfoldingIssue.lean:12:2-12:17: error: failed to synthesize
   MonadLog (StateM Nat)
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/eraseInsts.lean.expected.out b/tests/lean/eraseInsts.lean.expected.out
index d4bbcf4593..7f87845271 100644
--- a/tests/lean/eraseInsts.lean.expected.out
+++ b/tests/lean/eraseInsts.lean.expected.out
@@ -1,3 +1,3 @@
 eraseInsts.lean:12:22-12:27: error: failed to synthesize
   HAdd Foo Foo ?m
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/forErrors.lean.expected.out b/tests/lean/forErrors.lean.expected.out
index 911b25b697..f08536e449 100644
--- a/tests/lean/forErrors.lean.expected.out
+++ b/tests/lean/forErrors.lean.expected.out
@@ -1,3 +1,3 @@
 forErrors.lean:3:29-3:30: error: failed to synthesize
   ToStream α ?m
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/kernelMVarBug.lean.expected.out b/tests/lean/kernelMVarBug.lean.expected.out
index 70cd682386..8a6972e4d3 100644
--- a/tests/lean/kernelMVarBug.lean.expected.out
+++ b/tests/lean/kernelMVarBug.lean.expected.out
@@ -1,3 +1,3 @@
 kernelMVarBug.lean:5:15-5:20: error: failed to synthesize
   HAdd α α α
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/macroStack.lean.expected.out b/tests/lean/macroStack.lean.expected.out
index 9cfb577c7c..686732ebd8 100644
--- a/tests/lean/macroStack.lean.expected.out
+++ b/tests/lean/macroStack.lean.expected.out
@@ -11,7 +11,7 @@ while expanding
 macroStack.lean:11:9-11:15: error: invalid use of `(<- ...)`, must be nested inside a 'do' expression
 macroStack.lean:17:0-17:6: error: failed to synthesize
   HAdd Nat String ?m
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 with resulting expansion
   binop% HAdd.hAdd✝ (x + x✝) x✝¹
 while expanding
diff --git a/tests/lean/macroSwizzle.lean.expected.out b/tests/lean/macroSwizzle.lean.expected.out
index b250009a78..7900d1a430 100644
--- a/tests/lean/macroSwizzle.lean.expected.out
+++ b/tests/lean/macroSwizzle.lean.expected.out
@@ -1,6 +1,6 @@
 macroSwizzle.lean:4:7-4:23: error: failed to synthesize
   HAdd Bool String ?m
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 macroSwizzle.lean:6:7-6:10: error: application type mismatch
   Nat.succ "x"
 argument
diff --git a/tests/lean/openScoped.lean.expected.out b/tests/lean/openScoped.lean.expected.out
index 0a23b21693..529a44c3d9 100644
--- a/tests/lean/openScoped.lean.expected.out
+++ b/tests/lean/openScoped.lean.expected.out
@@ -1,7 +1,7 @@
 openScoped.lean:1:7-1:14: error: unknown identifier 'epsilon'
 openScoped.lean:4:2-4:24: error: failed to synthesize
   Decidable (f = g)
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 Classical.epsilon.{u} {α : Sort u} [h : Nonempty α] (p : α → Prop) : α
 openScoped.lean:15:7-15:14: error: unknown identifier 'epsilon'
 openScoped.lean:20:7-20:14: error: unknown identifier 'epsilon'
diff --git a/tests/lean/prvCtor.lean.expected.out b/tests/lean/prvCtor.lean.expected.out
index e3c95f1e05..6493d7e393 100644
--- a/tests/lean/prvCtor.lean.expected.out
+++ b/tests/lean/prvCtor.lean.expected.out
@@ -7,7 +7,7 @@ prvCtor.lean:27:7-27:8: error: unknown identifier 'a'
 prvCtor.lean:29:25-29:27: error: overloaded, errors 
   failed to synthesize
     EmptyCollection (Name "hello")
-  Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+  Additional diagnostic information may be available using the `set_option diagnostics true` command.
   
   invalid {...} notation, constructor for `Name` is marked as private
 prvCtor.lean:31:25-31:34: error: invalid ⟨...⟩ notation, constructor for `Name` is marked as private
diff --git a/tests/lean/run/1163.lean b/tests/lean/run/1163.lean
index 26685b4548..928dd171bf 100644
--- a/tests/lean/run/1163.lean
+++ b/tests/lean/run/1163.lean
@@ -16,7 +16,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `0` cannot be used in a context where the expected type is
   Bool
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 def x : Bool := 0
@@ -29,7 +29,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `0` cannot be used in a context where the expected type is
   Bool
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 theorem result4 : False := by -- Does not generate a `sorry` warning because there is an error
diff --git a/tests/lean/run/345.lean b/tests/lean/run/345.lean
index a00bb02d27..2a887e9c2d 100644
--- a/tests/lean/run/345.lean
+++ b/tests/lean/run/345.lean
@@ -6,7 +6,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `1` cannot be used in a context where the expected type is
   Sort _
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 axiom bla : 1
@@ -17,7 +17,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `1` cannot be used in a context where the expected type is
   Sort _
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 structure Foo where
@@ -29,7 +29,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `1` cannot be used in a context where the expected type is
   Sort _
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 inductive Bla (x : 1) : Type
diff --git a/tests/lean/run/3554.lean b/tests/lean/run/3554.lean
index 8458c60d40..4b8620ce88 100644
--- a/tests/lean/run/3554.lean
+++ b/tests/lean/run/3554.lean
@@ -6,11 +6,11 @@ set_option debug.moduleNameAtTimeout false
 /--
 error: (deterministic) timeout, maximum number of heartbeats (100) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout, maximum number of heartbeats (100) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 set_option maxHeartbeats 100 in
diff --git a/tests/lean/run/3996.lean b/tests/lean/run/3996.lean
index dba0ec5f5a..71af507e51 100644
--- a/tests/lean/run/3996.lean
+++ b/tests/lean/run/3996.lean
@@ -17,7 +17,7 @@ instance instB10000 : B 10000 where
 /--
 error: failed to synthesize
   A
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 #synth A -- should fail quickly
diff --git a/tests/lean/run/4203.lean b/tests/lean/run/4203.lean
index bb3fc788d9..8816a0e2bc 100644
--- a/tests/lean/run/4203.lean
+++ b/tests/lean/run/4203.lean
@@ -14,7 +14,7 @@ def IsGood [DecidableEq dOut] [DecidableEq dOut₂] (Λ : Mappish dIn dOut) (Λ
 /--
 error: failed to synthesize
   Fintype v
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 def MappishOrder [DecidableEq dIn] : Preorder
diff --git a/tests/lean/run/4365.lean b/tests/lean/run/4365.lean
index 29afb1caff..cde7a72745 100644
--- a/tests/lean/run/4365.lean
+++ b/tests/lean/run/4365.lean
@@ -37,7 +37,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `1` cannot be used in a context where the expected type is
   String
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 #check (1 : String)
@@ -48,7 +48,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `1` cannot be used in a context where the expected type is
   Bool
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 #check (1 : Bool)
@@ -59,7 +59,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `1` cannot be used in a context where the expected type is
   Bool → Nat
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 #check (1 : Bool → Nat)
@@ -70,7 +70,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `0` cannot be used in a context where the expected type is
   String
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 def foo : String :=
diff --git a/tests/lean/run/by_cases.lean b/tests/lean/run/by_cases.lean
index b76280fff7..ba75bcd62b 100644
--- a/tests/lean/run/by_cases.lean
+++ b/tests/lean/run/by_cases.lean
@@ -13,7 +13,7 @@ example (p : Prop) : True := by
 /--
 error: failed to synthesize
   Decidable p
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 example (p : Prop) : True := by
diff --git a/tests/lean/run/diagnosticsMsgOptional.lean b/tests/lean/run/diagnosticsMsgOptional.lean
index 257cfa860e..c9ae1886af 100644
--- a/tests/lean/run/diagnosticsMsgOptional.lean
+++ b/tests/lean/run/diagnosticsMsgOptional.lean
@@ -5,7 +5,7 @@
 /--
 error: failed to synthesize
   Coe Nat Int
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 #synth Coe Nat Int
diff --git a/tests/lean/run/guard_msgs.lean b/tests/lean/run/guard_msgs.lean
index c215bc5fa1..4d8d5cc255 100644
--- a/tests/lean/run/guard_msgs.lean
+++ b/tests/lean/run/guard_msgs.lean
@@ -51,7 +51,7 @@ error: failed to synthesize
 numerals are polymorphic in Lean, but the numeral `22` cannot be used in a context where the expected type is
   α
 due to the absence of the instance above
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs(error) in
 example : α := 22
@@ -107,7 +107,7 @@ Lax whitespace
 /--
 error: failed to synthesize
   DecidableEq (Nat → Nat)
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs (whitespace := lax) in
 #synth DecidableEq (Nat → Nat)
@@ -115,7 +115,7 @@ Additional diagnostic information may be available by using the `set_option diag
 /--
 error: failed to synthesize
   DecidableEq (Nat → Nat)
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs (whitespace := lax) in
 #synth DecidableEq (Nat → Nat)
diff --git a/tests/lean/run/isDefEqProjIssue.lean b/tests/lean/run/isDefEqProjIssue.lean
index e71137102d..aa4ed6320c 100644
--- a/tests/lean/run/isDefEqProjIssue.lean
+++ b/tests/lean/run/isDefEqProjIssue.lean
@@ -53,35 +53,35 @@ where
 /--
 error: (deterministic) timeout at `whnf`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout at `isDefEq`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout at `elaborator`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout at `isDefEq`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout at `isDefEq`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout at `elaborator`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout at `isDefEq`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 ---
 error: (deterministic) timeout at `whnf`, maximum number of heartbeats (400) has been reached
 Use `set_option maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 -/
 #guard_msgs in
 set_option backward.isDefEq.lazyWhnfCore false in
diff --git a/tests/lean/sanitychecks.lean.expected.out b/tests/lean/sanitychecks.lean.expected.out
index 67a8f2eaf0..be2ec02383 100644
--- a/tests/lean/sanitychecks.lean.expected.out
+++ b/tests/lean/sanitychecks.lean.expected.out
@@ -9,7 +9,7 @@ sanitychecks.lean:4:8-4:32: error: 'partial' theorems are not allowed, 'partial'
 sanitychecks.lean:7:7-7:31: error: 'unsafe' theorems are not allowed
 sanitychecks.lean:10:0-10:23: error: failed to synthesize
   Inhabited False
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 sanitychecks.lean:18:12-18:20: error: invalid use of 'partial', 'Foo.unsound3' is not a function
   False
 sanitychecks.lean:20:0-20:54: error: failed to compile partial definition 'Foo.unsound4', failed to show that type is inhabited and non empty
diff --git a/tests/lean/scopedLocalInsts.lean.expected.out b/tests/lean/scopedLocalInsts.lean.expected.out
index d4bc1c5699..1fa532bbcc 100644
--- a/tests/lean/scopedLocalInsts.lean.expected.out
+++ b/tests/lean/scopedLocalInsts.lean.expected.out
@@ -1,12 +1,12 @@
 scopedLocalInsts.lean:12:6-12:39: error: failed to synthesize
   ToString A
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 "A.mk 10 20"
 scopedLocalInsts.lean:21:6-21:39: error: failed to synthesize
   ToString A
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 "{ x := 10, y := 20 }"
 scopedLocalInsts.lean:32:6-32:39: error: failed to synthesize
   ToString A
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 "A.mk 10 20"
diff --git a/tests/lean/semicolonOrLinebreak.lean.expected.out b/tests/lean/semicolonOrLinebreak.lean.expected.out
index 190bbfee00..c5311fe000 100644
--- a/tests/lean/semicolonOrLinebreak.lean.expected.out
+++ b/tests/lean/semicolonOrLinebreak.lean.expected.out
@@ -7,4 +7,4 @@ term has type
   Nat
 semicolonOrLinebreak.lean:20:2-20:9: error: failed to synthesize
   Singleton ?m Point
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/setLit.lean.expected.out b/tests/lean/setLit.lean.expected.out
index c2da77acbd..442d3c3eee 100644
--- a/tests/lean/setLit.lean.expected.out
+++ b/tests/lean/setLit.lean.expected.out
@@ -1,12 +1,12 @@
 setLit.lean:22:19-22:21: error: overloaded, errors 
   failed to synthesize
     EmptyCollection String
-  Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+  Additional diagnostic information may be available using the `set_option diagnostics true` command.
   
   fields missing: 'data'
 setLit.lean:24:31-24:38: error: overloaded, errors 
   failed to synthesize
     Singleton Nat String
-  Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+  Additional diagnostic information may be available using the `set_option diagnostics true` command.
   
   24:33 'val' is not a field of structure 'String'
diff --git a/tests/lean/tcloop.lean.expected.out b/tests/lean/tcloop.lean.expected.out
index dff58ab124..1b0a21d9dc 100644
--- a/tests/lean/tcloop.lean.expected.out
+++ b/tests/lean/tcloop.lean.expected.out
@@ -1,3 +1,3 @@
 tcloop.lean:14:2-14:15: error: (deterministic) timeout at `typeclass`, maximum number of heartbeats (20000) has been reached
 Use `set_option synthInstance.maxHeartbeats <num>` to set the limit.
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
diff --git a/tests/lean/typeOf.lean.expected.out b/tests/lean/typeOf.lean.expected.out
index 53f3810095..2eae46dce7 100644
--- a/tests/lean/typeOf.lean.expected.out
+++ b/tests/lean/typeOf.lean.expected.out
@@ -1,9 +1,9 @@
 typeOf.lean:11:22-11:25: error: failed to synthesize
   HAdd Nat Nat Bool
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 typeOf.lean:12:0-12:5: error: failed to synthesize
   HAdd Bool Nat Nat
-Additional diagnostic information may be available by using the `set_option diagnostics true` command.
+Additional diagnostic information may be available using the `set_option diagnostics true` command.
 typeOf.lean:20:56-20:62: error: invalid reassignment, term has type
   Bool : Type
 but is expected to have type