diff --git a/appveyor.yml b/appveyor.yml
index b20604dce..6bf286fbd 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -16,6 +16,7 @@ install:
   - ps: (new-object net.webclient).DownloadFile('https://raw.github.com/pypa/pip/master/contrib/get-pip.py', 'C:\get-pip.py')
   # appveyor has python 2.7.6 x86 preinstalled, but in the wrong directory, this works around this
   - ps: if ($env:pythonurl -eq "http://www.python.org/ftp/python/2.7.6/python-2.7.6.msi") {mi c:\python27 c:\python}
+  - set PATH=C:\Python;%PATH%
   - C:\Python\python.exe c:\get-pip.py
   - C:\Python\Scripts\pip.exe install wheel
 
diff --git a/pythonnet/src/console/pythonconsole.cs b/pythonnet/src/console/pythonconsole.cs
index 2184c8730..26fc756d5 100644
--- a/pythonnet/src/console/pythonconsole.cs
+++ b/pythonnet/src/console/pythonconsole.cs
@@ -9,6 +9,7 @@
 
 using System;
 using System.Reflection;
+using System.Collections.Generic;
 using Python.Runtime;
 
 namespace Python.Runtime {
@@ -19,6 +20,9 @@ private PythonConsole() {}
 
     [STAThread]
     public static int Main(string[] args) {
+	// reference the static assemblyLoader to stop it being optimized away
+        AssemblyLoader a = assemblyLoader;
+
         string [] cmd = Environment.GetCommandLineArgs();
         PythonEngine.Initialize();
 
@@ -31,16 +35,27 @@ public static int Main(string[] args) {
     // Register a callback function to load embedded assmeblies.
     // (Python.Runtime.dll is included as a resource)
     private sealed class AssemblyLoader {
+        Dictionary<string, Assembly> loadedAssemblies;
+
         public AssemblyLoader() {
+            loadedAssemblies = new Dictionary<string, Assembly>();
+
             AppDomain.CurrentDomain.AssemblyResolve += (sender, args) => {
-                String resourceName = new AssemblyName(args.Name).Name + ".dll";
+                string shortName = args.Name.Split(',')[0];
+                String resourceName = shortName + ".dll";
+
+                if (loadedAssemblies.ContainsKey(resourceName)) {
+                    return loadedAssemblies[resourceName];
+                }
 
                 // looks for the assembly from the resources and load it
                 using (var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(resourceName)) {
                     if (stream != null) {
                         Byte[] assemblyData = new Byte[stream.Length];
                         stream.Read(assemblyData, 0, assemblyData.Length);
-                        return Assembly.Load(assemblyData);
+                        Assembly assembly = Assembly.Load(assemblyData);
+                        loadedAssemblies[resourceName] = assembly;
+                        return assembly;
                     }
                 }
 
diff --git a/pythonnet/src/runtime/assemblymanager.cs b/pythonnet/src/runtime/assemblymanager.cs
index b07cde1c2..291301466 100644
--- a/pythonnet/src/runtime/assemblymanager.cs
+++ b/pythonnet/src/runtime/assemblymanager.cs
@@ -30,6 +30,7 @@ internal class AssemblyManager {
         static ResolveEventHandler rhandler;
         static Dictionary<string, int> probed;
         static List<Assembly> assemblies;
+        static Dictionary<string, Assembly> loadedAssemblies;
         internal static List<string> pypath;
 
         private AssemblyManager() {}
@@ -46,6 +47,7 @@ internal static void Initialize() {
             probed = new Dictionary<string, int>(32);
             //generics = new Dictionary<string, Dictionary<string, string>>();
             assemblies = new List<Assembly>(16);
+            loadedAssemblies = new Dictionary<string, Assembly>();
             pypath = new List<string>(16);
 
             AppDomain domain = AppDomain.CurrentDomain;
@@ -202,7 +204,19 @@ public static Assembly LoadAssemblyPath(string name) {
             string path = FindAssembly(name);
             Assembly assembly = null;
             if (path != null) {
-                try   { assembly = Assembly.LoadFrom(path); }
+                if (loadedAssemblies.ContainsKey(path)) {
+                    return loadedAssemblies[path];
+                }
+                // Avoid using Assembly.LoadFrom as referenced assemblies that exist
+                // in the same path will be loaded directly from there, rather than
+                // using other versions already loaded. This is a problem if there
+                // is a Python.Runtime.dll in the same folder as the assembly being
+                // loaded, as that will result in two instances being loaded.
+                try   {
+                    byte[] bytes = System.IO.File.ReadAllBytes(path);
+                    assembly = Assembly.Load(bytes);
+                    loadedAssemblies[path] = assembly;
+                }
                 catch {}
             }
             return assembly;
diff --git a/pythonnet/src/testing/threadtest.cs b/pythonnet/src/testing/threadtest.cs
index a31fd9768..caad9fcf4 100644
--- a/pythonnet/src/testing/threadtest.cs
+++ b/pythonnet/src/testing/threadtest.cs
@@ -39,35 +39,43 @@ public class ThreadTest {
 
         public static string CallEchoString(string arg) {
             IntPtr gs = PythonEngine.AcquireLock();
-            if (module == null) {
-                module = PythonEngine.ModuleFromString("tt", testmod);
+            try {
+                if (module == null) {
+                    module = PythonEngine.ModuleFromString("tt", testmod);
+                }
+                PyObject func = module.GetAttr("echostring");
+                PyString parg = new PyString(arg);
+                PyObject temp = func.Invoke(parg);
+                string result = (string)temp.AsManagedObject(typeof(String));
+                func.Dispose();
+                parg.Dispose();
+                temp.Dispose();
+                return result;
+            }
+            finally {
+                PythonEngine.ReleaseLock(gs);
             }
-            PyObject func = module.GetAttr("echostring");
-            PyString parg = new PyString(arg);
-            PyObject temp = func.Invoke(parg);
-            string result = (string)temp.AsManagedObject(typeof(String));
-            func.Dispose();
-            parg.Dispose();
-            temp.Dispose();
-            PythonEngine.ReleaseLock(gs);
-            return result;
         }
 
         public static string CallEchoString2(string arg) {
             IntPtr gs = PythonEngine.AcquireLock();
-            if (module == null) {
-                module = PythonEngine.ModuleFromString("tt", testmod);
-            }
+            try {
+                if (module == null) {
+                    module = PythonEngine.ModuleFromString("tt", testmod);
+                }
 
-            PyObject func = module.GetAttr("echostring2");
-            PyString parg = new PyString(arg);
-            PyObject temp = func.Invoke(parg);
-            string result = (string)temp.AsManagedObject(typeof(String));
-            func.Dispose();
-            parg.Dispose();
-            temp.Dispose();
-            PythonEngine.ReleaseLock(gs);
-            return result;
+                PyObject func = module.GetAttr("echostring2");
+                PyString parg = new PyString(arg);
+                PyObject temp = func.Invoke(parg);
+                string result = (string)temp.AsManagedObject(typeof(String));
+                func.Dispose();
+                parg.Dispose();
+                temp.Dispose();
+                return result;
+            }
+            finally {
+                PythonEngine.ReleaseLock(gs);
+            }
         }