diff --git a/services/web/public/coffee/models/File.coffee b/services/web/public/coffee/models/File.coffee
index 3a59bab5fb..d4fc8b006f 100644
--- a/services/web/public/coffee/models/File.coffee
+++ b/services/web/public/coffee/models/File.coffee
@@ -7,7 +7,7 @@ define [
 
 
 		previewUrl: () ->
-			extension = @get("name").split(".").pop()
+			extension = @get("name").split(".").pop()?.toLowerCase()
 			needsConverting = (["eps", "pdf"].indexOf(extension) != -1)
 			queryString = if needsConverting then "?format=png" else ""
 			url = "#{@downloadUrl()}#{queryString}"