diff --git a/lib/impressionist/models/active_record/impression.rb b/lib/impressionist/models/active_record/impression.rb
index 710c446..f211b98 100644
--- a/lib/impressionist/models/active_record/impression.rb
+++ b/lib/impressionist/models/active_record/impression.rb
@@ -10,11 +10,12 @@ class Impression < ActiveRecord::Base
   private
 
   def update_impressions_counter_cache
-    impressionable_class = self.impressionable_type.constantize
-
-    if impressionable_class.impressionist_counter_cache_options
-      resouce = impressionable_class.find(self.impressionable_id)
-      resouce.try(:update_impressionist_counter_cache)
+    if self.impressionable_type && self.impressionable_id
+      impressionable_class = self.impressionable_type.constantize
+      if impressionable_class.impressionist_counter_cache_options
+        resouce = impressionable_class.find(self.impressionable_id)
+        resouce.try(:update_impressionist_counter_cache)
+      end
     end
   end
 end