diff --git a/AppKit/CPApplication.j b/AppKit/CPApplication.j
index c8debf421..04b7032ad 100644
--- a/AppKit/CPApplication.j
+++ b/AppKit/CPApplication.j
@@ -1041,7 +1041,7 @@ var _CPAppBootstrapperActions = nil;
 {
 }
 
-+ (void)actions
++ (CPArray)actions
 {
     return [@selector(bootstrapPlatform), @selector(loadDefaultTheme), @selector(loadMainCibFile)];
 }
@@ -1076,7 +1076,7 @@ var _CPAppBootstrapperActions = nil;
     return YES;
 }
 
-+ (void)blendDidFinishLoading:(CPBundle)aBundle
++ (void)blendDidFinishLoading:(CPThemeBlend)aThemeBlend
 {
     [CPTheme setDefaultTheme:[CPTheme themeNamed:[CPApplication defaultThemeName]]];
 
diff --git a/AppKit/CPView.j b/AppKit/CPView.j
index c0a2d87d2..a04a4dc59 100644
--- a/AppKit/CPView.j
+++ b/AppKit/CPView.j
@@ -2291,7 +2291,7 @@ setBoundsOrigin:
     return [_themeAttributes[aName] value];
 }
 
-- (void)currentValueForThemeAttribute:(CPString)aName
+- (id)currentValueForThemeAttribute:(CPString)aName
 {
     if (!_themeAttributes || !_themeAttributes[aName])
         [CPException raise:CPInvalidArgumentException reason:[self className] + " does not contain theme attribute '" + aName + "'"];
diff --git a/AppKit/CPWindow/CPWindow.j b/AppKit/CPWindow/CPWindow.j
index c3891cb11..61b203988 100644
--- a/AppKit/CPWindow/CPWindow.j
+++ b/AppKit/CPWindow/CPWindow.j
@@ -1504,7 +1504,7 @@ CPTexturedBackgroundWindowMask
     [_inclusiveRegisteredDraggedTypes unionSet:pasteboardTypes];
 }
 
-- (void)_noteUnregisteredDraggedTypes:(CPArray)pasteboardTypes
+- (void)_noteUnregisteredDraggedTypes:(CPSet)pasteboardTypes
 {
     if (!pasteboardTypes)
         return;
diff --git a/AppKit/CPWindow/_CPWindowView.j b/AppKit/CPWindow/_CPWindowView.j
index 984ebe3d9..c71770b91 100644
--- a/AppKit/CPWindow/_CPWindowView.j
+++ b/AppKit/CPWindow/_CPWindowView.j
@@ -228,7 +228,7 @@ var _CPWindowViewResizeIndicatorImage = nil;
     }
 }
 
-- (CPImage)showsResizeIndicator
+- (BOOL)showsResizeIndicator
 {
     return _resizeIndicator !== nil;
 }
diff --git a/AppKit/Platform/CPPlatformWindow.j b/AppKit/Platform/CPPlatformWindow.j
index a915f2a17..d9716d77f 100644
--- a/AppKit/Platform/CPPlatformWindow.j
+++ b/AppKit/Platform/CPPlatformWindow.j
@@ -137,7 +137,7 @@ var PrimaryPlatformWindow   = NULL;
     return frame;
 }
 
-- (void)usableContentFrame
+- (CGRect)usableContentFrame
 {
     return [self visibleFrame];
 }
diff --git a/Foundation/CPKeyedUnarchiver.j b/Foundation/CPKeyedUnarchiver.j
index 2a30e82fe..f35dfde39 100644
--- a/Foundation/CPKeyedUnarchiver.j
+++ b/Foundation/CPKeyedUnarchiver.j
@@ -193,7 +193,7 @@ var _CPKeyedUnarchiverArrayClass                                            = Ni
 }
 
 /* @ignore */
-- (void)_decodeDictionaryOfObjectsForKey:(CPString)aKey
+- (CPDictionary)_decodeDictionaryOfObjectsForKey:(CPString)aKey
 {
     var object = [_plistObject objectForKey:aKey];
     
diff --git a/Objective-J/Debug.js b/Objective-J/Debug.js
index 3975a0368..184224418 100644
--- a/Objective-J/Debug.js
+++ b/Objective-J/Debug.js
@@ -167,12 +167,13 @@ GLOBAL(objj_debug_typecheck) = function(expectedType, object)
         {
             return;
         }
-        else if (object && object.isa)
+        else if (object !== undefined && object.isa)
         {
             var theClass = object.isa;
+
             for (; theClass; theClass = theClass.super_class)
-            if (theClass === objjClass)
-                return;
+                if (theClass === objjClass)
+                    return;
         }
     }
     else
@@ -189,6 +190,6 @@ GLOBAL(objj_debug_typecheck) = function(expectedType, object)
         actualType = GETMETA(object).name;
     else
         actualType = typeof object;
-        
+
     throw ("expected=" + expectedType + ", actual=" + actualType);
 }