diff --git a/macros/src/main/scala/barstools/macros/CostMetric.scala b/macros/src/main/scala/barstools/macros/CostMetric.scala
index 3b9de124..a6111d2e 100644
--- a/macros/src/main/scala/barstools/macros/CostMetric.scala
+++ b/macros/src/main/scala/barstools/macros/CostMetric.scala
@@ -126,6 +126,10 @@ object DefaultMetric extends CostMetric with CostMetricCompanion {
         else (mem.src.width / p) * m //Waste the extra maskbits
       }
     }
+    val maskPenalty = (memMask, libMask) match {
+      case (None, Some(m)) => 0.001
+      case (_, _) => 0
+    }
     val depthCost = math.ceil(mem.src.depth.toDouble / lib.src.depth.toDouble)
     val widthCost = math.ceil(memWidth.toDouble / lib.src.width.toDouble)
     val bitsCost = (lib.src.depth * lib.src.width).toDouble
@@ -134,7 +138,7 @@ object DefaultMetric extends CostMetric with CostMetricCompanion {
     val bitsWasted = depthCost * widthCost * bitsCost - requestedBits
     val wastedConst = 0.05 // 0 means waste as few bits with no regard for instance count
     val costPerInst = wastedConst * depthCost * widthCost
-    Some(1.0 * bitsWasted / requestedBits + costPerInst)
+    Some(1.0 * bitsWasted / requestedBits + costPerInst + maskPenalty)
   }
 
   override def commandLineParams = Map()