Index: PC/_winreg.c
===================================================================
--- PC/_winreg.c	(revision 84990)
+++ PC/_winreg.c	(working copy)
@@ -1193,19 +1193,27 @@
     DWORD typ;
     PyObject *obData;
     PyObject *retVal;
+    CPINFO info;
 
     if (!PyArg_ParseTuple(args, "Oi:EnumValue", &obKey, &index))
         return NULL;
     if (!PyHKEY_AsHKEY(obKey, &hKey, FALSE))
         return NULL;
 
+    if (!GetCPInfo(CP_ACP, &info))
+        return PyErr_SetFromWindowsErrWithFunction(GetLastError(),
+                                                   "GetCPInfo");
+    assert(info.MaxCharSize >= 1);
+
     if ((rc = RegQueryInfoKey(hKey, NULL, NULL, NULL, NULL, NULL, NULL,
                               NULL,
                               &retValueSize, &retDataSize, NULL, NULL))
         != ERROR_SUCCESS)
         return PyErr_SetFromWindowsErrWithFunction(rc,
                                                    "RegQueryInfoKey");
-    ++retValueSize;    /* include null terminators */
+    /* This value should be large enough to store the value name in ANSI
+       characters. (include null terminator) */
+    retValueSize = (retValueSize * info.MaxCharSize) + 1;
     ++retDataSize;
     bufDataSize = retDataSize;
     bufValueSize = retValueSize;