diff --git a/src/Compiler/Checking/CheckDeclarations.fs b/src/Compiler/Checking/CheckDeclarations.fs
index d858368cd6..705d9b6d7d 100644
--- a/src/Compiler/Checking/CheckDeclarations.fs
+++ b/src/Compiler/Checking/CheckDeclarations.fs
@@ -870,7 +870,7 @@ module MutRecBindingChecking =
                             error(Error(FSComp.SR.tcEnumerationsMayNotHaveMembers(), (trimRangeToLine m))) 
 
                         match classMemberDef, containerInfo with
-                        | SynMemberDefn.ImplicitCtor (vis, Attributes attrs, SynSimplePats.SimplePats(spats, _), thisIdOpt, xmlDoc, m), ContainerInfo(_, Some(MemberOrValContainerInfo(tcref, _, baseValOpt, safeInitInfo, _))) ->
+                        | SynMemberDefn.ImplicitCtor (vis, Attributes attrs, SynSimplePats.SimplePats(spats, _), thisIdOpt, xmlDoc, m, _), ContainerInfo(_, Some(MemberOrValContainerInfo(tcref, _, baseValOpt, safeInitInfo, _))) ->
                             if tcref.TypeOrMeasureKind = TyparKind.Measure then
                                 error(Error(FSComp.SR.tcMeasureDeclarationsRequireStaticMembers(), m))
 
@@ -4211,13 +4211,13 @@ module TcDeclarations =
 
             let hasSelfReferentialCtor = 
                 members |> List.exists (function 
-                    | SynMemberDefn.ImplicitCtor (_, _, _, thisIdOpt, _, _) 
+                    | SynMemberDefn.ImplicitCtor (selfIdentifier = thisIdOpt) 
                     | SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(thisIdOpt=thisIdOpt))) -> thisIdOpt.IsSome
                     | _ -> false)
 
             let implicitCtorSynPats = 
                 members |> List.tryPick (function 
-                    | SynMemberDefn.ImplicitCtor (_, _, (SynSimplePats.SimplePats _ as spats), _, _, _) -> Some spats
+                    | SynMemberDefn.ImplicitCtor (ctorArgs = SynSimplePats.SimplePats _ as spats) -> Some spats
                     | _ -> None)
 
             // An ugly bit of code to pre-determine if a type has a nullary constructor, prior to establishing the 
@@ -4226,7 +4226,7 @@ module TcDeclarations =
                 members |> List.exists (function 
                     | SynMemberDefn.Member(memberDefn=SynBinding(valData=SynValData(memberFlags=Some memberFlags); headPat = SynPatForConstructorDecl SynPatForNullaryArgs)) -> 
                         memberFlags.MemberKind=SynMemberKind.Constructor 
-                    | SynMemberDefn.ImplicitCtor (_, _, SynSimplePats.SimplePats(spats, _), _, _, _) -> isNil spats
+                    | SynMemberDefn.ImplicitCtor (ctorArgs = SynSimplePats.SimplePats(spats, _)) -> isNil spats
                     | _ -> false)
             let repr = SynTypeDefnSimpleRepr.General(kind, inherits, slotsigs, fields, isConcrete, isIncrClass, implicitCtorSynPats, m)
             let isAtOriginalTyconDefn = not (isAugmentationTyconDefnRepr repr)
diff --git a/src/Compiler/Service/FSharpParseFileResults.fs b/src/Compiler/Service/FSharpParseFileResults.fs
index 929d38b957..000320352a 100644
--- a/src/Compiler/Service/FSharpParseFileResults.fs
+++ b/src/Compiler/Service/FSharpParseFileResults.fs
@@ -886,7 +886,7 @@ type FSharpParseFileResults(diagnostics: FSharpDiagnostic[], input: ParsedInput,
                         match memb with
                         | SynMemberDefn.LetBindings (binds, _, _, _) -> yield! walkBinds binds
                         | SynMemberDefn.AutoProperty (synExpr = synExpr) -> yield! walkExpr true synExpr
-                        | SynMemberDefn.ImplicitCtor (_, _, _, _, _, m) -> yield! checkRange m
+                        | SynMemberDefn.ImplicitCtor (range = m) -> yield! checkRange m
                         | SynMemberDefn.Member (bind, _) -> yield! walkBind bind
                         | SynMemberDefn.GetSetMember (getBinding, setBinding, _, _) ->
                             match getBinding, setBinding with
diff --git a/src/Compiler/Service/ServiceParseTreeWalk.fs b/src/Compiler/Service/ServiceParseTreeWalk.fs
index 8415ec401f..7e932bdb83 100644
--- a/src/Compiler/Service/ServiceParseTreeWalk.fs
+++ b/src/Compiler/Service/ServiceParseTreeWalk.fs
@@ -901,7 +901,7 @@ module SyntaxTraversal =
                     traverseSynBinding path getBinding
                     |> Option.orElseWith (fun () -> traverseSynBinding path setBinding)
 
-            | SynMemberDefn.ImplicitCtor (_synAccessOption, _synAttributes, simplePats, _identOption, _doc, _range) ->
+            | SynMemberDefn.ImplicitCtor (ctorArgs = simplePats) ->
                 match simplePats with
                 | SynSimplePats.SimplePats (simplePats, _) -> visitor.VisitSimplePats(path, simplePats)
                 | _ -> None
diff --git a/src/Compiler/Service/ServiceParsedInputOps.fs b/src/Compiler/Service/ServiceParsedInputOps.fs
index a8344a59e9..b4739fe73e 100644
--- a/src/Compiler/Service/ServiceParsedInputOps.fs
+++ b/src/Compiler/Service/ServiceParsedInputOps.fs
@@ -897,7 +897,7 @@ module ParsedInput =
                 | None, Some binding -> walkBinding binding
                 | Some getBinding, Some setBinding -> walkBinding getBinding |> Option.orElseWith (fun () -> walkBinding setBinding)
 
-            | SynMemberDefn.ImplicitCtor (_, Attributes attrs, SynSimplePats.SimplePats (simplePats, _), _, _, _) ->
+            | SynMemberDefn.ImplicitCtor (attributes = Attributes attrs; ctorArgs = SynSimplePats.SimplePats (simplePats, _)) ->
                 List.tryPick walkAttribute attrs
                 |> Option.orElseWith (fun () -> List.tryPick walkSimplePat simplePats)
 
@@ -1892,7 +1892,7 @@ module ParsedInput =
             | SynMemberDefn.GetSetMember (getBinding, setBinding, _, _) ->
                 Option.iter walkBinding getBinding
                 Option.iter walkBinding setBinding
-            | SynMemberDefn.ImplicitCtor (_, Attributes attrs, SynSimplePats.SimplePats (simplePats, _), _, _, _) ->
+            | SynMemberDefn.ImplicitCtor (attributes = Attributes attrs; ctorArgs = SynSimplePats.SimplePats (simplePats, _)) ->
                 List.iter walkAttribute attrs
                 List.iter walkSimplePat simplePats
             | SynMemberDefn.ImplicitInherit (t, e, _, _) ->
diff --git a/src/Compiler/SyntaxTree/SyntaxTree.fs b/src/Compiler/SyntaxTree/SyntaxTree.fs
index aa5535914d..1acd2eae68 100644
--- a/src/Compiler/SyntaxTree/SyntaxTree.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTree.fs
@@ -1410,7 +1410,8 @@ type SynMemberDefn =
         ctorArgs: SynSimplePats *
         selfIdentifier: Ident option *
         xmlDoc: PreXmlDoc *
-        range: range
+        range: range *
+        trivia: SynMemberDefnImplicitCtorTrivia
 
     | ImplicitInherit of inheritType: SynType * inheritArgs: SynExpr * inheritAlias: Ident option * range: range
 
diff --git a/src/Compiler/SyntaxTree/SyntaxTree.fsi b/src/Compiler/SyntaxTree/SyntaxTree.fsi
index 5190b8fd73..73040c5324 100644
--- a/src/Compiler/SyntaxTree/SyntaxTree.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTree.fsi
@@ -1588,7 +1588,8 @@ type SynMemberDefn =
         ctorArgs: SynSimplePats *
         selfIdentifier: Ident option *
         xmlDoc: PreXmlDoc *
-        range: range
+        range: range *
+        trivia: SynMemberDefnImplicitCtorTrivia
 
     /// An implicit inherit definition, 'inherit <typ>(args...) as base'
     | ImplicitInherit of inheritType: SynType * inheritArgs: SynExpr * inheritAlias: Ident option * range: range
diff --git a/src/Compiler/SyntaxTree/SyntaxTrivia.fs b/src/Compiler/SyntaxTree/SyntaxTrivia.fs
index dea3bfbc31..18a5c30d50 100644
--- a/src/Compiler/SyntaxTree/SyntaxTrivia.fs
+++ b/src/Compiler/SyntaxTree/SyntaxTrivia.fs
@@ -316,6 +316,9 @@ type SynMemberGetSetTrivia =
         SetKeyword: range option
     }
 
+[<NoEquality; NoComparison>]
+type SynMemberDefnImplicitCtorTrivia = { AsKeyword: range option }
+
 [<NoEquality; NoComparison>]
 type SynArgPatsNamePatPairsTrivia = { ParenRange: range }
 
diff --git a/src/Compiler/SyntaxTree/SyntaxTrivia.fsi b/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
index c76e3e9953..b57db229ee 100644
--- a/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
+++ b/src/Compiler/SyntaxTree/SyntaxTrivia.fsi
@@ -405,6 +405,14 @@ type SynMemberGetSetTrivia =
         SetKeyword: range option
     }
 
+/// Represents additional information for SynMemberDefn.ImplicitCtor
+[<NoEquality; NoComparison>]
+type SynMemberDefnImplicitCtorTrivia =
+    {
+        /// The syntax range of the `as` keyword
+        AsKeyword: range option
+    }
+
 /// Represents additional information for SynArgPats.NamePatPairs
 [<NoEquality; NoComparison>]
 type SynArgPatsNamePatPairsTrivia =
diff --git a/src/Compiler/pars.fsy b/src/Compiler/pars.fsy
index a44a1e6952..9e53f78b9d 100644
--- a/src/Compiler/pars.fsy
+++ b/src/Compiler/pars.fsy
@@ -1543,7 +1543,7 @@ tyconDefn:
        let mEquals = rhs parseState 7
        // Gets the XML doc comments prior to the implicit constructor
        let xmlDoc = grabXmlDoc(parseState, $2, 2)
-       let memberCtorPattern = SynMemberDefn.ImplicitCtor (vis, $2, spats, az, xmlDoc, rangeOfLid lid)
+       let memberCtorPattern = SynMemberDefn.ImplicitCtor (vis, $2, spats, Option.map snd az, xmlDoc, rangeOfLid lid, { AsKeyword = Option.map fst az })
        let tcDefRepr = 
          match tcDefRepr with
          | SynTypeDefnRepr.ObjectModel (k, cspec, m) -> SynTypeDefnRepr.ObjectModel (k, memberCtorPattern :: cspec, m)
@@ -1865,7 +1865,7 @@ classDefnMember:
         let m = unionRanges mWholeBindLhs $7.Range |> unionRangeWithXmlDoc xmlDoc
         let mEquals = rhs parseState 6
         let expr = $7
-        let valSynData = SynValData (Some CtorMemberFlags, SynValInfo([SynInfo.InferSynArgInfoFromPat $4], SynInfo.unnamedRetVal), $5) 
+        let valSynData = SynValData (Some CtorMemberFlags, SynValInfo([SynInfo.InferSynArgInfoFromPat $4], SynInfo.unnamedRetVal), Option.map snd $5)
         let vis = $2 
         let declPat = SynPat.LongIdent (SynLongIdent([mkSynId (rhs parseState 3) "new"], [], [None]), None, Some noInferredTypars, SynArgPats.Pats [$4], vis, rhs parseState 3)
         // Check that 'SynPatForConstructorDecl' matches this correctly
@@ -2021,7 +2021,7 @@ optAsSpec:
 
 asSpec: 
   | AS ident
-     { $2 } 
+     { rhs parseState 1, $2 } 
 
 optBaseSpec: 
   | baseSpec
diff --git a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl
index 8ce003becd..020defbf2e 100644
--- a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl
+++ b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl
@@ -7309,6 +7309,8 @@ FSharp.Compiler.Syntax.SynMemberDefn+GetSetMember: Microsoft.FSharp.Core.FSharpO
 FSharp.Compiler.Syntax.SynMemberDefn+GetSetMember: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding] memberDefnForSet
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Syntax.SynSimplePats ctorArgs
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Syntax.SynSimplePats get_ctorArgs()
+FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia get_trivia()
+FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia trivia
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Text.Range range
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Xml.PreXmlDoc get_xmlDoc()
@@ -7406,7 +7408,7 @@ FSharp.Compiler.Syntax.SynMemberDefn: Boolean get_IsValField()
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewAbstractSlot(FSharp.Compiler.Syntax.SynValSig, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberDefnAbstractSlotTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewAutoProperty(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], Boolean, FSharp.Compiler.Syntax.Ident, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynType], FSharp.Compiler.Syntax.SynMemberKind, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Xml.PreXmlDoc, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewGetSetMember(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia)
-FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitCtor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], FSharp.Compiler.Syntax.SynSimplePats, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Xml.PreXmlDoc, FSharp.Compiler.Text.Range)
+FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitCtor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], FSharp.Compiler.Syntax.SynSimplePats, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Xml.PreXmlDoc, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitInherit(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynExpr, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewInherit(FSharp.Compiler.Syntax.SynType, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewInterface(FSharp.Compiler.Syntax.SynType, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynMemberDefn]], FSharp.Compiler.Text.Range)
@@ -9627,6 +9629,10 @@ FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.C
 FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_WithKeyword()
 FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Void .ctor(FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.SyntaxTrivia.GetSetKeywords])
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] AsKeyword
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_AsKeyword()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: System.String ToString()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: FSharp.Compiler.Text.Range WithKeyword
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: FSharp.Compiler.Text.Range get_WithKeyword()
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] AndKeyword
diff --git a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl
index 8ce003becd..020defbf2e 100644
--- a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl
+++ b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl
@@ -7309,6 +7309,8 @@ FSharp.Compiler.Syntax.SynMemberDefn+GetSetMember: Microsoft.FSharp.Core.FSharpO
 FSharp.Compiler.Syntax.SynMemberDefn+GetSetMember: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding] memberDefnForSet
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Syntax.SynSimplePats ctorArgs
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Syntax.SynSimplePats get_ctorArgs()
+FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia get_trivia()
+FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia trivia
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Text.Range get_range()
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Text.Range range
 FSharp.Compiler.Syntax.SynMemberDefn+ImplicitCtor: FSharp.Compiler.Xml.PreXmlDoc get_xmlDoc()
@@ -7406,7 +7408,7 @@ FSharp.Compiler.Syntax.SynMemberDefn: Boolean get_IsValField()
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewAbstractSlot(FSharp.Compiler.Syntax.SynValSig, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberDefnAbstractSlotTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewAutoProperty(Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], Boolean, FSharp.Compiler.Syntax.Ident, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynType], FSharp.Compiler.Syntax.SynMemberKind, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Syntax.SynMemberFlags, FSharp.Compiler.Xml.PreXmlDoc, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], FSharp.Compiler.Syntax.SynExpr, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewGetSetMember(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynBinding], FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia)
-FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitCtor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], FSharp.Compiler.Syntax.SynSimplePats, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Xml.PreXmlDoc, FSharp.Compiler.Text.Range)
+FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitCtor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.SynAccess], Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynAttributeList], FSharp.Compiler.Syntax.SynSimplePats, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Xml.PreXmlDoc, FSharp.Compiler.Text.Range, FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewImplicitInherit(FSharp.Compiler.Syntax.SynType, FSharp.Compiler.Syntax.SynExpr, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewInherit(FSharp.Compiler.Syntax.SynType, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Syntax.Ident], FSharp.Compiler.Text.Range)
 FSharp.Compiler.Syntax.SynMemberDefn: FSharp.Compiler.Syntax.SynMemberDefn NewInterface(FSharp.Compiler.Syntax.SynType, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.Syntax.SynMemberDefn]], FSharp.Compiler.Text.Range)
@@ -9627,6 +9629,10 @@ FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.C
 FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_WithKeyword()
 FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: System.String ToString()
 FSharp.Compiler.SyntaxTrivia.SynMemberDefnAutoPropertyTrivia: Void .ctor(FSharp.Compiler.SyntaxTrivia.SynLeadingKeyword, Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range], Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.SyntaxTrivia.GetSetKeywords])
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] AsKeyword
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] get_AsKeyword()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: System.String ToString()
+FSharp.Compiler.SyntaxTrivia.SynMemberDefnImplicitCtorTrivia: Void .ctor(Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range])
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: FSharp.Compiler.Text.Range WithKeyword
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: FSharp.Compiler.Text.Range get_WithKeyword()
 FSharp.Compiler.SyntaxTrivia.SynMemberGetSetTrivia: Microsoft.FSharp.Core.FSharpOption`1[FSharp.Compiler.Text.Range] AndKeyword
diff --git a/tests/service/SyntaxTreeTests/MemberTests.fs b/tests/service/SyntaxTreeTests/MemberTests.fs
index 2cd0eaafa4..9b6cfa3537 100644
--- a/tests/service/SyntaxTreeTests/MemberTests.fs
+++ b/tests/service/SyntaxTreeTests/MemberTests.fs
@@ -362,3 +362,26 @@ type X =
         assertRange (4, 13) (4, 19) mInlineGet
         assertRange (5, 12) (5, 18) mInlineSet
     | ast -> Assert.Fail $"Could not get valid AST, got {ast}"
+
+[<Test>]
+let ``ImplicitCtor with as keyword`` () =
+    let parseResults = 
+        getParseResults
+            """
+type internal CompilerStateCache(readAllBytes: string -> byte[], projectOptions: FSharpProjectOptions)
+//#if !NO_TYPEPROVIDERS
+    as this =
+//#else
+//     =
+// #endif
+    class end
+"""
+
+    match parseResults with
+    | ParsedInput.ImplFile (ParsedImplFileInput (contents = [ SynModuleOrNamespace.SynModuleOrNamespace(decls = [
+        SynModuleDecl.Types(
+            typeDefns = [ SynTypeDefn(implicitConstructor = Some (SynMemberDefn.ImplicitCtor(trivia = { AsKeyword = Some mAs }))) ]
+        )
+    ]) ])) ->
+        assertRange (4, 4) (4, 6) mAs
+    | ast -> Assert.Fail $"Could not get valid AST, got {ast}"