Index: PC/_winreg.c
===================================================================
--- PC/_winreg.c	(revision 84990)
+++ PC/_winreg.c	(working copy)
@@ -1193,6 +1193,7 @@
     DWORD typ;
     PyObject *obData;
     PyObject *retVal;
+    const DWORD maxValueSize = 32767;
 
     if (!PyArg_ParseTuple(args, "Oi:EnumValue", &obKey, &index))
         return NULL;
@@ -1233,16 +1234,36 @@
         if (rc != ERROR_MORE_DATA)
             break;
 
-        bufDataSize *= 2;
-        tmpBuf = (char *)PyMem_Realloc(retDataBuf, bufDataSize);
-        if (tmpBuf == NULL) {
-            PyErr_NoMemory();
-            retVal = NULL;
-            goto fail;
+        if (bufDataSize < retDataSize) {
+            bufDataSize = retDataSize;
+            tmpBuf = (char *)PyMem_Realloc(retDataBuf, bufDataSize);
+            if (tmpBuf == NULL) {
+                PyErr_NoMemory();
+                retVal = NULL;
+                goto fail;
+            }
+            retDataBuf = tmpBuf;
+            retDataSize = bufDataSize;
+        } else {
+            if (bufValueSize >= maxValueSize) {
+                PyErr_SetString(PyExc_RuntimeError,
+                    "RegEnumValue required value size greater than %d",
+                    maxValueSize);
+                retVal = NULL;
+                goto fail;
+            }
+            bufValueSize *= 2;
+            if (bufValueSize > maxValueSize)
+                bufValueSize = maxValueSize;
+            tmpBuf = (char *)PyMem_Realloc(retValueBuf, bufValueSize);
+            if (tmpBuf == NULL) {
+                PyErr_NoMemory();
+                retVal = NULL;
+                goto fail;
+            }
+            retValueBuf = tmpBuf;
+            retValueSize = bufValueSize;
         }
-        retDataBuf = tmpBuf;
-        retDataSize = bufDataSize;
-        retValueSize = bufValueSize;
     }
 
     if (rc != ERROR_SUCCESS) {