diff --git a/HTMLKit/CSSAttributeSelector.h b/HTMLKit/CSSAttributeSelector.h
index 812e29e..b7e6a99 100644
--- a/HTMLKit/CSSAttributeSelector.h
+++ b/HTMLKit/CSSAttributeSelector.h
@@ -8,6 +8,7 @@
 
 #import <Foundation/Foundation.h>
 #import "CSSSelector.h"
+#import "CSSSimpleSelector.h"
 
 typedef NS_ENUM(NSUInteger, CSSAttributeSelectorType)
 {
@@ -20,7 +21,7 @@ typedef NS_ENUM(NSUInteger, CSSAttributeSelectorType)
 	CSSAttributeSelectorHyphen
 };
 
-@interface CSSAttributeSelector : CSSSelector
+@interface CSSAttributeSelector : CSSSelector <CSSSimpleSelector>
 
 @property (nonatomic, assign) CSSAttributeSelectorType type;
 @property (nonatomic, copy) NSString *name;
diff --git a/HTMLKit/CSSSelectors.h b/HTMLKit/CSSSelectors.h
index 30d21f3..d147704 100644
--- a/HTMLKit/CSSSelectors.h
+++ b/HTMLKit/CSSSelectors.h
@@ -7,5 +7,6 @@
 //
 
 #import "CSSSelector.h"
+#import "CSSSimpleSelector.h"
 #import "CSSTypeSelector.h"
 #import "CSSAttributeSelector.h"
diff --git a/HTMLKit/CSSTypeSelector.h b/HTMLKit/CSSTypeSelector.h
index acc6b6e..1d5c82e 100644
--- a/HTMLKit/CSSTypeSelector.h
+++ b/HTMLKit/CSSTypeSelector.h
@@ -8,8 +8,9 @@
 
 #import <Foundation/Foundation.h>
 #import "CSSSelector.h"
+#import "CSSSimpleSelector.h"
 
-@interface CSSTypeSelector : CSSSelector
+@interface CSSTypeSelector : CSSSelector <CSSSimpleSelector>
 
 @property (nonatomic, copy) NSString *type;