diff --git a/include/rapidjson/document.h b/include/rapidjson/document.h
index ef5b301..a059429 100644
--- a/include/rapidjson/document.h
+++ b/include/rapidjson/document.h
@@ -801,6 +801,9 @@ public:
 	}
 
 private:
+	// Prohibit assignment
+	GenericDocument& operator=(const GenericDocument&);
+
 	void ClearStack() {
 		if (Allocator::kNeedFree)
 			while (stack_.GetSize() > 0)	// Here assumes all elements in stack array are GenericValue (Member is actually 2 GenericValue objects)
diff --git a/test/unittest/documenttest.cpp b/test/unittest/documenttest.cpp
index 5dd4f35..82fc67d 100644
--- a/test/unittest/documenttest.cpp
+++ b/test/unittest/documenttest.cpp
@@ -82,3 +82,11 @@ TEST(Document, UTF16_Document) {
 
 	EXPECT_EQ(0, wcscmp(L"Wed Oct 30 17:13:20 +0000 2012", s.GetString()));
 }
+
+// Issue 22: Memory corruption via operator=
+// Fixed by making unimplemented assignment operator private.
+//TEST(Document, Assignment) {
+//	Document d1;
+//	Document d2;
+//	d1 = d2;
+//}