diff --git a/LMAlertView.podspec b/LMAlertView.podspec
index 21da812..fee5c0b 100644
--- a/LMAlertView.podspec
+++ b/LMAlertView.podspec
@@ -8,10 +8,10 @@ Pod::Spec.new do |s|
   s.source   = { :git => 'https://github.com/lmcd/LMAlertView.git', :tag => 'v1.1.0' }
   s.requires_arc = true
 
-  s.ios.deployment_target = '7.0'
+  s.ios.deployment_target = ‘7.0’
   s.dependency 'RBBAnimation', '~> 0.3.0'
   s.dependency 'CAAnimationBlocks', '~> 0.0.1'
 
   s.public_header_files = 'LMAlertView/*.h'
   s.source_files = 'LMAlertView', 'LMAlertView/**/*.{h,m}'
-end
\ No newline at end of file
+end
diff --git a/LMAlertView/CALayer+ModalAlert.m b/LMAlertView/CALayer+ModalAlert.m
index 085311c..4e86b94 100644
--- a/LMAlertView/CALayer+ModalAlert.m
+++ b/LMAlertView/CALayer+ModalAlert.m
@@ -26,8 +26,13 @@ + (void)load
 - (UIWindow *)windowForView:(UIView *)view
 {
 	UIView *tempView = view;
-	
+    if (![tempView respondsToSelector:@selector(superview)]) {
+        return nil;
+    }
 	while (tempView.superview != nil) {
+        if (![tempView respondsToSelector:@selector(superview)]) {
+            break;
+        }
 		tempView = tempView.superview;
 		
 		if ([tempView isKindOfClass:[UIWindow class]]) {