diff --git a/a5/src/APL/Tests.hs b/a5/src/APL/Tests.hs
index 1066ec4..57f70d4 100644
--- a/a5/src/APL/Tests.hs
+++ b/a5/src/APL/Tests.hs
@@ -5,6 +5,7 @@ module APL.Tests
 where
 
 import APL.AST (Exp (..), subExp, VName, printExp)
+import APL.Eval (eval, runEval)
 import APL.Parser (parseAPL, keywords)
 import APL.Error (isVariableError, isDomainError, isTypeError)
 import APL.Check (checkExp)
@@ -114,11 +115,13 @@ parsePrinted e = case (parseAPL "input" (printExp e)) of
   Right e' -> e == e'
 
 onlyCheckedErrors :: Exp -> Bool
-onlyCheckedErrors _ = undefined
+onlyCheckedErrors e = case runEval (eval e) of
+  Right _ -> True
+  Left err -> err `elem` (checkExp e)
 
 properties :: [(String, Property)]
 properties =
   [ ("expCoverage", property expCoverage)
   , ("parsePrinted", property (withMaxSuccess 10000 parsePrinted))
-  , ("onlyCheckedErrors", property onlyCheckedErrors)
+  , ("onlyCheckedErrors", property (withMaxSuccess 1000000 onlyCheckedErrors))
   ]