1 files changed, 26 insertions, 10 deletions

diff --git a/src/WixToolset.Core.Native/WixNativeExe.cs b/src/WixToolset.Core.Native/WixNativeExe.cs
index 90ab0042..3bd340bc 100644
--- a/src/WixToolset.Core.Native/WixNativeExe.cs
+++ b/src/WixToolset.Core.Native/WixNativeExe.cs
@@ -12,16 +12,12 @@ namespace WixToolset.Core.Native
     internal class WixNativeExe
     {
         private const int FiveMinutesInMilliseconds = 300000;
-        private static readonly string PathToWixNativeExe;
+        private static readonly object PathToWixNativeExeLock = new object();
+        private static string PathToWixNativeExe;
 
         private readonly string commandLine;
         private readonly List<string> stdinLines = new List<string>();
 
-        static WixNativeExe()
-        {
-            PathToWixNativeExe = Path.Combine(Path.GetDirectoryName(new Uri(Assembly.GetExecutingAssembly().CodeBase).LocalPath), "wixnative.x86.exe");
-        }
-
         public WixNativeExe(params object[] args)
         {
             this.commandLine = String.Join(" ", QuoteArgumentsAsNecesary(args));
@@ -39,10 +35,7 @@ namespace WixToolset.Core.Native
 
         public IEnumerable<string> Run()
         {
-            if (!File.Exists(PathToWixNativeExe))
-            {
-                throw new FileNotFoundException($"Could not find internal piece of WiX Toolset at: {PathToWixNativeExe}", PathToWixNativeExe);
-            }
+            EnsurePathToWixNativeExeSet();
 
             var wixNativeInfo = new ProcessStartInfo(PathToWixNativeExe, this.commandLine)
             {
@@ -88,6 +81,29 @@ namespace WixToolset.Core.Native
             return stdoutLines;
         }
 
+        private static void EnsurePathToWixNativeExeSet()
+        {
+            lock (PathToWixNativeExeLock)
+            {
+                if (String.IsNullOrEmpty(PathToWixNativeExe))
+                {
+                    var path = Path.Combine(Path.GetDirectoryName(new Uri(Assembly.GetExecutingAssembly().CodeBase).LocalPath), @"x86\wixnative.x86.exe");
+
+                    if (!File.Exists(path))
+                    {
+                        path = Path.Combine(Path.GetDirectoryName(new Uri(Assembly.GetExecutingAssembly().CodeBase).LocalPath), "wixnative.x86.exe");
+
+                        if (!File.Exists(path))
+                        {
+                            throw new FileNotFoundException($"Could not find internal piece of WiX Toolset at: {path}", path);
+                        }
+                    }
+
+                    PathToWixNativeExe = path;
+                }
+            }
+        }
+
         private static IEnumerable<string> QuoteArgumentsAsNecesary(object[] args)
         {
             foreach (var arg in args)