diff --git a/lm_eval/mixins.py b/lm_eval/mixins.py
index ac2e292986..61de932102 100644
--- a/lm_eval/mixins.py
+++ b/lm_eval/mixins.py
@@ -35,7 +35,8 @@ def majority_vote(
             self,
             sampled_answers: List[T],
             correct_answer: T,
-            is_equiv : Callable[[T, T], bool] = lambda x, y: x==y
+            is_equiv : Callable[[T, T], bool] = lambda x, y: x==y,
+            invalid_answer: T = None
     ):
         """
         Performs majority voting on a list of candidate answers. 
@@ -47,6 +48,9 @@ def majority_vote(
             correct_answer: T, ground truth.
             is_equiv: Callable[[T, T], bool], a function that determines when two answers 
                 should be treated as equivalent. Default is T-equivalence, i.e `lambda x y: x==y`.
+            invalid_answer: T, answer that corresponds to a parsing failure from a sample. 
+                If passed as arg, no votes for invalid answer should be counted, but it should
+                count against pass_rate.
         Returns:
             acc: int, 0/1 for correct/incorrect
             pass_rate: float, proportion of `sampled_answers` equivalent to `correct_answer`
@@ -57,7 +61,17 @@ def majority_vote(
             return 0, 0, []
 
         answer_votes = {}
-        for answer in sampled_answers:
+
+        # we only count votes for successfully parsed answers, as we choose not
+        # to allow a model to vote for [invalidanswer] as its response.
+        # however, we do want to calculate pass_rate as a function of 
+        # total K = *num. sampled answers*.
+        if invalid_answer:
+            valid_sampled_answers = [answer for answer in sampled_answers if answer != invalid_answer]
+        else:
+            valid_sampled_answers = sampled_answers
+
+        for answer in valid_sampled_answers:
             if answer in answer_votes: 
                 answer_votes[answer] += 1
             else: