diff --git a/cli/gen-package/codegen/Gen/Elm/Declare.elm b/cli/gen-package/codegen/Gen/Elm/Declare.elm
index 873114d1..7ae3fd3b 100644
--- a/cli/gen-package/codegen/Gen/Elm/Declare.elm
+++ b/cli/gen-package/codegen/Gen/Elm/Declare.elm
@@ -26,7 +26,7 @@ fn :
     -> Elm.Expression
     -> (Elm.Expression -> Elm.Expression)
     -> Elm.Expression
-fn fnArg fnArg0 fnArg1 =
+fn fn_Arg fn_Arg0 fn_Arg1 =
     Elm.apply
         (Elm.value
              { importFrom = [ "Elm", "Declare" ]
@@ -54,7 +54,7 @@ fn fnArg fnArg0 fnArg1 =
                      )
              }
         )
-        [ Elm.string fnArg, fnArg0, Elm.functionReduced "fnUnpack" fnArg1 ]
+        [ Elm.string fn_Arg, fn_Arg0, Elm.functionReduced "fnUnpack" fn_Arg1 ]
 
 
 {-| fn2: 
@@ -1340,7 +1340,7 @@ call_ :
     }
 call_ =
     { fn =
-        \fnArg fnArg0 fnArg1 ->
+        \fn_Arg fn_Arg0 fn_Arg1 ->
             Elm.apply
                 (Elm.value
                      { importFrom = [ "Elm", "Declare" ]
@@ -1376,7 +1376,7 @@ call_ =
                              )
                      }
                 )
-                [ fnArg, fnArg0, fnArg1 ]
+                [ fn_Arg, fn_Arg0, fn_Arg1 ]
     , fn2 =
         \fn2Arg fn2Arg0 fn2Arg1 fn2Arg2 ->
             Elm.apply
diff --git a/cli/gen-package/codegen/Gen/Elm/Let.elm b/cli/gen-package/codegen/Gen/Elm/Let.elm
index 484573fa..6f128efb 100644
--- a/cli/gen-package/codegen/Gen/Elm/Let.elm
+++ b/cli/gen-package/codegen/Gen/Elm/Let.elm
@@ -155,7 +155,7 @@ fn :
     -> (Elm.Expression -> Elm.Expression)
     -> Elm.Expression
     -> Elm.Expression
-fn fnArg fnArg0 fnArg1 fnArg2 =
+fn fn_Arg fn_Arg0 fn_Arg1 fn_Arg2 =
     Elm.apply
         (Elm.value
              { importFrom = [ "Elm", "Let" ]
@@ -203,10 +203,10 @@ fn fnArg fnArg0 fnArg1 fnArg2 =
                      )
              }
         )
-        [ Elm.string fnArg
-        , fnArg0
-        , Elm.functionReduced "fnUnpack" fnArg1
-        , fnArg2
+        [ Elm.string fn_Arg
+        , fn_Arg0
+        , Elm.functionReduced "fnUnpack" fn_Arg1
+        , fn_Arg2
         ]
 
 
@@ -622,7 +622,7 @@ call_ =
                 )
                 [ recordArg, recordArg0, recordArg1 ]
     , fn =
-        \fnArg fnArg0 fnArg1 fnArg2 ->
+        \fn_Arg fn_Arg0 fn_Arg1 fn_Arg2 ->
             Elm.apply
                 (Elm.value
                      { importFrom = [ "Elm", "Let" ]
@@ -671,7 +671,7 @@ call_ =
                              )
                      }
                 )
-                [ fnArg, fnArg0, fnArg1, fnArg2 ]
+                [ fn_Arg, fn_Arg0, fn_Arg1, fn_Arg2 ]
     , fn2 =
         \fn2Arg fn2Arg0 fn2Arg1 fn2Arg2 fn2Arg3 ->
             Elm.apply
diff --git a/cli/gen-package/src/Generate.elm b/cli/gen-package/src/Generate.elm
index 7e4f3664..20bf50ab 100644
--- a/cli/gen-package/src/Generate.elm
+++ b/cli/gen-package/src/Generate.elm
@@ -416,7 +416,7 @@ block2Maker thisModule block =
                                     )
                                 |> Gen.Elm.record
                     in
-                    Elm.fn (Elm.Arg.varWith (name ++ "_Arg") lambdaArgType) lambdaValue
+                    Elm.fn (Elm.Arg.varWith (toArgName name) lambdaArgType) lambdaValue
                         |> Just
 
                 _ ->
@@ -534,7 +534,7 @@ annotationNamed thisModule name tags =
             Elm.function
                 (List.indexedMap
                     (\i arg ->
-                        ( name ++ "_Arg" ++ String.fromInt i
+                        ( toArgName name ++ String.fromInt i
                         , Just (Annotation.named elmAnnotation "Annotation")
                         )
                     )
@@ -630,7 +630,7 @@ aliasNamed docAlias =
             Elm.function
                 (List.indexedMap
                     (\i arg ->
-                        ( docAlias.name ++ "_Arg" ++ String.fromInt i
+                        ( toArgName docAlias.name ++ String.fromInt i
                         , Just (Annotation.named elmAnnotation "Annotation")
                         )
                     )
@@ -884,7 +884,7 @@ captureFunction baseName tipe captured =
             in
             captureFunction baseName
                 two
-                { arguments = ( baseName ++ "_Arg", Just unpacked.annotation ) :: captured.arguments
+                { arguments = ( toArgName baseName, Just unpacked.annotation ) :: captured.arguments
                 , unpackers = unpacked.unpacker :: captured.unpackers
                 }
 
@@ -893,11 +893,20 @@ captureFunction baseName tipe captured =
                 unpacked =
                     unpackArg baseName tipe
             in
-            { arguments = ( baseName ++ "_Arg", Just unpacked.annotation ) :: captured.arguments
+            { arguments = ( toArgName baseName, Just unpacked.annotation ) :: captured.arguments
             , unpackers = unpacked.unpacker :: captured.unpackers
             }
 
 
+toArgName : String -> String
+toArgName baseName =
+    if baseName == "fn" then
+        "fn_Arg"
+
+    else
+        baseName ++ "Arg"
+
+
 unpackArgForLambdas :
     String
     -> Elm.Type.Type