1 files changed, 4 insertions, 2 deletions
diff --git a/src/main/scala/firrtl/passes/CheckFlows.scala b/src/main/scala/firrtl/passes/CheckFlows.scala
index 3fdb3443..b4ce4d5f 100644
--- a/src/main/scala/firrtl/passes/CheckFlows.scala
+++ b/src/main/scala/firrtl/passes/CheckFlows.scala
@@ -6,9 +6,9 @@ import firrtl._
 import firrtl.ir._
 import firrtl.Utils._
 import firrtl.traversals.Foreachers._
-import firrtl.options.{Dependency, PreservesAll}
+import firrtl.options.Dependency
 
-object CheckFlows extends Pass with PreservesAll[Transform] {
+object CheckFlows extends Pass {
 
   override def prerequisites = Dependency(passes.ResolveFlows) +: firrtl.stage.Forms.WorkingIR
 
@@ -18,6 +18,8 @@ object CheckFlows extends Pass with PreservesAll[Transform] {
          Dependency[passes.InferWidths],
          Dependency[transforms.InferResets] )
 
+  override def invalidates(a: Transform) = false
+
   type FlowMap = collection.mutable.HashMap[String, Flow]
 
   implicit def toStr(g: Flow): String = g match {