diff --git a/lib/katip/change_logger.rb b/lib/katip/change_logger.rb
index 6b2f401..e83fba5 100644
--- a/lib/katip/change_logger.rb
+++ b/lib/katip/change_logger.rb
@@ -56,10 +56,8 @@ def parse_change_log
       tags = tags.split
       prev_begin = nil
 
-      if !tags.include?(@tag_from) or !tags.include?(@tag_to)
-        puts 'Could not find the given tags. Make sure that both of tags exist.'
-        puts 'Listing found tags:'
-        puts tags
+      if (!@tag_from.nil? && !tags.include?(@tag_from)) || (!@tag_to.nil? && !tags.include?(@tag_to))
+        show_not_found_message(tags)
         return output
       end
 
@@ -115,5 +113,11 @@ def parse_change_log
 
       output
     end
+
+    def show_not_found_message(tags)
+      puts 'Could not find the given tags. Make sure that given tags exist.'
+      puts 'Listing found tags:'
+      puts tags
+    end
   end
 end