diff --git a/Languages/IronPython/IronPython.Modules/_winreg.cs b/Languages/IronPython/IronPython.Modules/_winreg.cs
index 10a667e948..fce8db5316 100644
--- a/Languages/IronPython/IronPython.Modules/_winreg.cs
+++ b/Languages/IronPython/IronPython.Modules/_winreg.cs
@@ -265,6 +265,7 @@ public static PythonTuple EnumValue(object key, int index) {
         }
 
         private static void QueryValueExImpl(SafeRegistryHandle handle, string valueName, out int valueKind, out object value) {
+            valueName = valueName ?? ""; // it looks like RegQueryValueEx can fail with null, use empty string instead
             valueKind = 0;
             int dwRet;
             byte[] data = new byte[128];
@@ -278,6 +279,13 @@ private static void QueryValueExImpl(SafeRegistryHandle handle, string valueName
                 dwRet = RegQueryValueEx(handle, valueName, IntPtr.Zero, out valueKind, data, ref length);
             }
 
+            if (dwRet == PythonExceptions._WindowsError.ERROR_FILE_NOT_FOUND) {
+                throw PythonExceptions.CreateThrowable(PythonExceptions.WindowsError, PythonExceptions._WindowsError.ERROR_FILE_NOT_FOUND, "The system cannot find the file specified");
+            }
+            if (dwRet != ERROR_SUCCESS) {
+                throw PythonExceptions.CreateThrowable(PythonExceptions.WindowsError, dwRet);
+            }
+
             // convert the result into a Python object
 
             switch (valueKind) {