diff --git a/src/Fantomas.Tests/DataStructureTests.fs b/src/Fantomas.Tests/DataStructureTests.fs
index af37dacd68..f57fb2754a 100644
--- a/src/Fantomas.Tests/DataStructureTests.fs
+++ b/src/Fantomas.Tests/DataStructureTests.fs
@@ -1376,4 +1376,22 @@ let f' includeWeekend =
       if includeWeekend then
           "Saturday"
           "Sunday" ]
+"""
+
+[<Test>]
+let ``NamedIndexedPropertySet`` () =
+    formatSourceString false """analysisKey.Headers.Item(key) <- value
+"""  config
+    |> prepend newline
+    |> should equal """
+analysisKey.Headers.Item(key) <- value
+"""
+
+[<Test>]
+let ``DotNamedIndexedPropertySet`` () =
+    formatSourceString false """(foo()).Item(key) <- value
+"""  config
+    |> prepend newline
+    |> should equal """
+(foo()).Item(key) <- value
 """
\ No newline at end of file
diff --git a/src/Fantomas/CodePrinter.fs b/src/Fantomas/CodePrinter.fs
index 7d8ba320e5..3552decb6a 100644
--- a/src/Fantomas/CodePrinter.fs
+++ b/src/Fantomas/CodePrinter.fs
@@ -1153,6 +1153,10 @@ and genExpr astContext synExpr =
         !- (sprintf "%s <- " s) +> autoIndentNlnByFuture (genExpr astContext e)
     | DotIndexedGet(e, es) -> addParenIfAutoNln e (genExpr astContext) -- "." +> sepOpenLFixed +> genIndexers astContext es +> sepCloseLFixed
     | DotIndexedSet(e1, es, e2) -> addParenIfAutoNln e1 (genExpr astContext) -- ".[" +> genIndexers astContext es -- "] <- " +> genExpr astContext e2
+    | NamedIndexedPropertySet(ident, e1, e2) ->
+        !- ident +> genExpr astContext e1  -- " <- "  +> genExpr astContext e2
+    | DotNamedIndexedPropertySet(e, ident, e1, e2) ->
+       genExpr astContext e -- "." -- ident +> genExpr astContext e1 -- " <- "  +> genExpr astContext e2
     | DotGet(e, (s,_)) -> 
         let exprF = genExpr { astContext with IsInsideDotGet = true }
         addParenIfAutoNln e exprF -- (sprintf ".%s" s)
diff --git a/src/Fantomas/SourceParser.fs b/src/Fantomas/SourceParser.fs
index 696c89d5f8..b6761cc8e2 100644
--- a/src/Fantomas/SourceParser.fs
+++ b/src/Fantomas/SourceParser.fs
@@ -754,6 +754,16 @@ let (|DotIndexedSet|_|) = function
         Some(e1, es, e2)
     | _ -> None
 
+let (|NamedIndexedPropertySet|_|) = function
+    | SynExpr.NamedIndexedPropertySet(LongIdentWithDots ident, e1, e2, _) ->
+        Some(ident, e1, e2)
+    | _ -> None
+
+let (|DotNamedIndexedPropertySet|_|) = function
+    | SynExpr.DotNamedIndexedPropertySet(e, LongIdentWithDots ident, e1, e2, _) ->
+        Some(e, ident, e1, e2)
+    | _ -> None
+
 let (|DotIndexedGet|_|) = function
     | SynExpr.DotIndexedGet(e1, es, _, _) ->
         Some(e1, es)