diff --git a/types/block_test.go b/types/block_test.go
index 4ed47dd9d..c18b2ef1e 100644
--- a/types/block_test.go
+++ b/types/block_test.go
@@ -274,7 +274,7 @@ func TestCommit(t *testing.T) {
 	require.NotNil(t, commit.BitArray())
 	assert.Equal(t, bits.NewBitArray(10).Size(), commit.BitArray().Size())
 
-	assert.Equal(t, voteSet.GetByIndex(0), commit.GetByIndex(0))
+	assert.Equal(t, voteWithoutExtension(voteSet.GetByIndex(0)), commit.GetByIndex(0))
 	assert.True(t, commit.IsCommit())
 }
 
@@ -571,8 +571,8 @@ func TestCommitToVoteSet(t *testing.T) {
 	voteSet2 := CommitToVoteSet(chainID, commit, valSet)
 
 	for i := int32(0); int(i) < len(vals); i++ {
-		vote1 := voteSet.GetByIndex(i)
-		vote2 := voteSet2.GetByIndex(i)
+		vote1 := voteWithoutExtension(voteSet.GetByIndex(i))
+		vote2 := voteWithoutExtension(voteSet2.GetByIndex(i))
 		vote3 := commit.GetVote(i)
 
 		vote1bz, err := vote1.ToProto().Marshal()
diff --git a/types/test_util.go b/types/test_util.go
index 55f56ebf5..8aea2f02c 100644
--- a/types/test_util.go
+++ b/types/test_util.go
@@ -46,3 +46,13 @@ func signAddVote(ctx context.Context, privVal PrivValidator, vote *Vote, voteSet
 	vote.ExtensionSignature = v.ExtensionSignature
 	return voteSet.AddVote(vote)
 }
+
+// Votes constructed from commits don't have extensions, because we don't store
+// the extensions themselves in the commit. This method is used to construct a
+// copy of a vote, but nil its extension and signature.
+func voteWithoutExtension(v *Vote) *Vote {
+	vc := v.Copy()
+	vc.Extension = nil
+	vc.ExtensionSignature = nil
+	return vc
+}