diff --git a/src/main/scala/tilelink/Edges.scala b/src/main/scala/tilelink/Edges.scala
index 1cbd311d5c8..6f323cada12 100644
--- a/src/main/scala/tilelink/Edges.scala
+++ b/src/main/scala/tilelink/Edges.scala
@@ -273,17 +273,17 @@ class TLEdge(
 
   // Does the request need T permissions to be executed?
   def needT(a: TLBundleA): Bool = {
-    val acq_needT = MuxLookup(a.param, Wire(Bool()), Array(
+    val acq_needT = MuxLookup(a.param, WireDefault(Bool(), DontCare), Array(
       TLPermissions.NtoB -> false.B,
       TLPermissions.NtoT -> true.B,
       TLPermissions.BtoT -> true.B))
-    MuxLookup(a.opcode, Wire(Bool()), Array(
+    MuxLookup(a.opcode, WireDefault(Bool(), DontCare), Array(
       TLMessages.PutFullData    -> true.B,
       TLMessages.PutPartialData -> true.B,
       TLMessages.ArithmeticData -> true.B,
       TLMessages.LogicalData    -> true.B,
       TLMessages.Get            -> false.B,
-      TLMessages.Hint           -> MuxLookup(a.param, Wire(Bool()), Array(
+      TLMessages.Hint           -> MuxLookup(a.param, WireDefault(Bool(), DontCare), Array(
         TLHints.PREFETCH_READ   -> false.B,
         TLHints.PREFETCH_WRITE  -> true.B)),
       TLMessages.AcquireBlock   -> acq_needT,
@@ -406,6 +406,7 @@ class TLEdgeOut(
 
   def ProbeAck(fromSource: UInt, toAddress: UInt, lgSize: UInt, reportPermissions: UInt): TLBundleC = {
     val c = Wire(new TLBundleC(bundle))
+    c :#= DontCare
     c.opcode  := TLMessages.ProbeAck
     c.param   := reportPermissions
     c.size    := lgSize
@@ -421,6 +422,7 @@ class TLEdgeOut(
 
   def ProbeAck(fromSource: UInt, toAddress: UInt, lgSize: UInt, reportPermissions: UInt, data: UInt, corrupt: Bool): TLBundleC = {
     val c = Wire(new TLBundleC(bundle))
+    c :#= DontCare
     c.opcode  := TLMessages.ProbeAckData
     c.param   := reportPermissions
     c.size    := lgSize
@@ -446,6 +448,7 @@ class TLEdgeOut(
     require (manager.anySupportGet, s"TileLink: No managers visible from this edge support Gets, but one of these clients would try to request one: ${client.clients}")
     val legal = manager.supportsGetFast(toAddress, lgSize)
     val a = Wire(new TLBundleA(bundle))
+    a :#= DontCare
     a.opcode  := TLMessages.Get
     a.param   := 0.U
     a.size    := lgSize
@@ -464,6 +467,7 @@ class TLEdgeOut(
     require (manager.anySupportPutFull, s"TileLink: No managers visible from this edge support Puts, but one of these clients would try to request one: ${client.clients}")
     val legal = manager.supportsPutFullFast(toAddress, lgSize)
     val a = Wire(new TLBundleA(bundle))
+    a :#= DontCare
     a.opcode  := TLMessages.PutFullData
     a.param   := 0.U
     a.size    := lgSize
@@ -482,6 +486,7 @@ class TLEdgeOut(
     require (manager.anySupportPutPartial, s"TileLink: No managers visible from this edge support masked Puts, but one of these clients would try to request one: ${client.clients}")
     val legal = manager.supportsPutPartialFast(toAddress, lgSize)
     val a = Wire(new TLBundleA(bundle))
+    a :#= DontCare
     a.opcode  := TLMessages.PutPartialData
     a.param   := 0.U
     a.size    := lgSize
@@ -497,6 +502,7 @@ class TLEdgeOut(
     require (manager.anySupportArithmetic, s"TileLink: No managers visible from this edge support arithmetic AMOs, but one of these clients would try to request one: ${client.clients}")
     val legal = manager.supportsArithmeticFast(toAddress, lgSize)
     val a = Wire(new TLBundleA(bundle))
+    a :#= DontCare
     a.opcode  := TLMessages.ArithmeticData
     a.param   := atomic
     a.size    := lgSize
@@ -512,6 +518,7 @@ class TLEdgeOut(
     require (manager.anySupportLogical, s"TileLink: No managers visible from this edge support logical AMOs, but one of these clients would try to request one: ${client.clients}")
     val legal = manager.supportsLogicalFast(toAddress, lgSize)
     val a = Wire(new TLBundleA(bundle))
+    a :#= DontCare
     a.opcode  := TLMessages.LogicalData
     a.param   := atomic
     a.size    := lgSize