diff --git a/src/Paket.Core/PaketConfigFiles/LockFile.fs b/src/Paket.Core/PaketConfigFiles/LockFile.fs
index 91006224e4..6616cc2bed 100644
--- a/src/Paket.Core/PaketConfigFiles/LockFile.fs
+++ b/src/Paket.Core/PaketConfigFiles/LockFile.fs
@@ -884,7 +884,7 @@ type LockFile (fileName:string, groups: Map<GroupName,LockFileGroup>) =
 
     member this.GetOrderedPackageHull(groupName,referencesFile:ReferencesFile,targetProfileOpt) =
         let usedPackageKeys = HashSet<_>()
-        let toVisit = ref Set.empty
+        let toVisit = ref []
         let cliTools = ref Set.empty
         let resolution =
             match this.Groups |> Map.tryFind groupName with
@@ -920,15 +920,14 @@ type LockFile (fileName:string, groups: Map<GroupName,LockFileGroup>) =
                     usedPackageKeys.Add k |> ignore
 
                     let deps = this.GetDirectDependenciesOfSafe(groupName,p.Name,referencesFile.FileName)
-
-                    toVisit := Set.add (k,p,deps) !toVisit
+                    toVisit := List.append toVisit.contents [(k,p,deps)]
         | None -> ()
 
         let visited = Dictionary<_,_>()
 
-        while !toVisit <> Set.empty do
-            let current = Set.minElement !toVisit
-            toVisit := Set.remove current !toVisit
+        while !toVisit <> List.empty do
+            let current = toVisit.Value[0]
+            toVisit := toVisit.Value.Tail
 
             let visitKey,p,deps = current
             if visited.ContainsKey(visitKey) then ()
@@ -937,9 +936,9 @@ type LockFile (fileName:string, groups: Map<GroupName,LockFileGroup>) =
 
             let groupName,_packageName = visitKey
             for dep in deps do
-                let deps = this.GetDirectDependenciesOfSafe(groupName,dep,referencesFile.FileName)
+                let deps2 = this.GetDirectDependenciesOfSafe(groupName,dep,referencesFile.FileName)
                 let packagageSettings = { p with Settings = { p.Settings with Aliases = Map.empty }}
-                toVisit := Set.add ((groupName,dep),packagageSettings,deps) !toVisit
+                toVisit := List.append toVisit.contents [((groupName,dep),packagageSettings,deps2)]
 
         let emitted = HashSet<_>()
         [while visited.Count > 0 do