diff --git a/djangoapps/courseware/capa/responsetypes.py b/djangoapps/courseware/capa/responsetypes.py
index 9ba1bd6256..946e325fe6 100644
--- a/djangoapps/courseware/capa/responsetypes.py
+++ b/djangoapps/courseware/capa/responsetypes.py
@@ -48,12 +48,12 @@ class numericalresponse(object):
         ''' Display HTML for a numeric response '''
         student_answer = student_answers[self.answer_id]
         try:
-            correct = compare_with_tolerance (evaluator(dict(),dict(),student_answer), self.correct_answer, self.tolerance)
+            correct = compare_with_tolerance (evaluator(dict(),dict(),student_answer), complex(self.correct_answer), self.tolerance)
         # We should catch this explicitly. 
         # I think this is just pyparsing.ParseException, calc.UndefinedVariable:
         # But we'd need to confirm
         except: 
-            raise StudentInputError('Invalid input -- please use a number only')
+            raise #StudentInputError('Invalid input -- please use a number only')
 
         if correct:
             return {self.answer_id:'correct'}