diff --git a/include/ehs/Serializer.h b/include/ehs/Serializer.h
index 3de251c..e3e1c12 100644
--- a/include/ehs/Serializer.h
+++ b/include/ehs/Serializer.h
@@ -405,7 +405,9 @@ namespace ehs
 					inSize++;
 
 			N bSize = sizeof(T) * inSize;
-			N bSizeN = sizeof(T) * (inSize + 1);
+			N bSizeN = bSize;
+			if (!sizeKnown)
+				bSizeN += sizeof(T);
 
 			if (bSizeN > size - offset)
 			{