diff --git a/app.lua b/app.lua
index 5dd7af8..947f655 100644
--- a/app.lua
+++ b/app.lua
@@ -13,7 +13,11 @@
 function love.run()
   App.snapshot_love()
   -- Tests always run at the start.
+  Test_errors = {}
   App.run_tests()
+  if #Test_errors > 0 then
+    error('There were test failures:\n\n'..table.concat(Test_errors))
+  end
 
 --?   print('==')
   App.disable_tests()