diff --git a/types/block.go b/types/block.go
index 7b52d4b2..d607c2c1 100644
--- a/types/block.go
+++ b/types/block.go
@@ -224,6 +224,9 @@ func (v *Validation) Type() byte {
 }
 
 func (v *Validation) Size() int {
+	if v == nil {
+		return 0
+	}
 	return len(v.Precommits)
 }