diff --git a/app/models/page.rb b/app/models/page.rb
index 964b34e..ca43d9a 100644
--- a/app/models/page.rb
+++ b/app/models/page.rb
@@ -33,12 +33,14 @@ class Page
 
 	def assign_page_number
 		parent_page = self.parent_page
-		if parent_page.child_page.count == 0
-			number = 0
-		else
-			number = parent_page.child_page.max(:number) + 1
+		if !parent_page.nil?
+			if parent_page.child_page.count == 0
+				number = 0
+			else
+				number = parent_page.child_page.max(:number) + 1
+			end
+			self.number = number
 		end
-		self.number = number
 	end
 
 	def parent_pages