diff --git a/src/absil/ilwrite.fs b/src/absil/ilwrite.fs
index 993b78959b..127d5d0d39 100755
--- a/src/absil/ilwrite.fs
+++ b/src/absil/ilwrite.fs
@@ -3074,7 +3074,7 @@ module FileSystemUtilites =
 #if ENABLE_MONO_SUPPORT
       if runningOnMono then 
         try 
-            let monoPosix = Assembly.Load("Mono.Posix, Version=2.0.0.0, Culture=neutral, PublicKeyToken=0738eb9f132ed756")
+            let monoPosix = Assembly.Load("Mono.Posix, Version=4.0.0.0, Culture=neutral, PublicKeyToken=0738eb9f132ed756")
             if progress then eprintf "loading type Mono.Unix.UnixFileInfo...\n"
             let monoUnixFileInfo = monoPosix.GetType("Mono.Unix.UnixFileSystemInfo") 
             let fileEntry = monoUnixFileInfo.InvokeMember("GetFileSystemEntry", (BindingFlags.InvokeMethod ||| BindingFlags.Static ||| BindingFlags.Public), null, null, [| box filename |],System.Globalization.CultureInfo.InvariantCulture)
diff --git a/src/fsharp/CompileOps.fs b/src/fsharp/CompileOps.fs
index 3a0e7620bd..695c5093d6 100755
--- a/src/fsharp/CompileOps.fs
+++ b/src/fsharp/CompileOps.fs
@@ -2218,11 +2218,7 @@ type TcConfigBuilder =
           resolutionAssemblyFoldersConditions = ""              
           platform = None
           prefer32Bit = false
-#if ENABLE_MONO_SUPPORT
-          useSimpleResolution = runningOnMono
-#else
           useSimpleResolution = false
-#endif
           target = ConsoleExe
           debuginfo = false
           testFlagEmitFeeFeeAs100001 = false
diff --git a/src/fsharp/vs/service.fs b/src/fsharp/vs/service.fs
index 8e77c3e9da..4c32fd16f5 100755
--- a/src/fsharp/vs/service.fs
+++ b/src/fsharp/vs/service.fs
@@ -2525,12 +2525,7 @@ type BackgroundCompiler(projectCacheSize, keepAssemblyContents, keepAllBackgroun
             let useFsiAuxLib = defaultArg useFsiAuxLib true
             // Do we use a "FSharp.Core, 4.3.0.0" reference by default?
             let otherFlags = defaultArg otherFlags [| |]
-            let useSimpleResolution = 
-#if ENABLE_MONO_SUPPORT
-                runningOnMono || otherFlags |> Array.exists (fun x -> x = "--simpleresolution")
-#else
-                true
-#endif
+            let useSimpleResolution = otherFlags |> Array.exists (fun x -> x = "--simpleresolution")
             let loadedTimeStamp = defaultArg loadedTimeStamp DateTime.MaxValue // Not 'now', we don't want to force reloading
             let applyCompilerOptions tcConfigB  = 
                 let collect _name = ()