diff --git a/src/fsharp/FSharp.Core/prim-types.fs b/src/fsharp/FSharp.Core/prim-types.fs
index 96b417a47df..c86de74bda6 100644
--- a/src/fsharp/FSharp.Core/prim-types.fs
+++ b/src/fsharp/FSharp.Core/prim-types.fs
@@ -961,11 +961,11 @@ namespace Microsoft.FSharp.Core
                     let c = int64Order lenx1 leny1 
                     if c <> 0 then c else
                     let basex0 = int64 (x.GetLowerBound(0))
-                    let basex1 = int64 (x.GetLowerBound(1))
                     let basey0 = int64 (y.GetLowerBound(0))
-                    let basey1 = int64 (y.GetLowerBound(1))
                     let c = int64Order basex0 basey0
                     if c <> 0 then c else
+                    let basex1 = int64 (x.GetLowerBound(1))
+                    let basey1 = int64 (y.GetLowerBound(1))
                     let c = int64Order basex1 basey1
                     if c <> 0 then c else
                     let rec check0 i =