diff --git a/Foundation/CPDictionary.j b/Foundation/CPDictionary.j
index c352c1afa..a628db87f 100755
--- a/Foundation/CPDictionary.j
+++ b/Foundation/CPDictionary.j
@@ -84,8 +84,9 @@
 */
 + (id)alloc
 {
-	if ([self class] !== CPDictionary && [self class] !== CPMutableDictionary) return [super alloc];
-    return new CFMutableDictionary();
+	var result = new CFMutableDictionary();
+	if ([self class] !== CPDictionary && [self class] !== CPMutableDictionary) result.isa = [self class];
+    return result;
 }
 
 /*!
diff --git a/Foundation/CPString.j b/Foundation/CPString.j
index 87831a567..82570d1a4 100644
--- a/Foundation/CPString.j
+++ b/Foundation/CPString.j
@@ -135,7 +135,7 @@ var CPStringRegexSpecialCharacters = [
 */
 - (id)initWithString:(CPString)aString
 {
-    return String(aString);
+	return CreateSubclassableString(aString, [self class]);
 }
 
 /*!
@@ -796,6 +796,17 @@ var CPStringRegexSpecialCharacters = [
 
 @end
 
+var CreateSubclassableString = function(aString, aClass)
+{
+	if (aClass === CPString) return String(aString);
+	
+	var result = new String(aString);
+	
+	result.isa = aClass;
+	
+	return result;
+};
+
 var diacritics = [[192,198],[224,230],[231,231],[232,235],[236,239],[242,246],[249,252]]; // Basic Latin ; Latin-1 Supplement.
 var normalized = [65,97,99,101,105,111,117];