diff --git a/src/main/scala/diplomacy/Parameters.scala b/src/main/scala/diplomacy/Parameters.scala
index aa2e5bc3..10ceb162 100644
--- a/src/main/scala/diplomacy/Parameters.scala
+++ b/src/main/scala/diplomacy/Parameters.scala
@@ -19,8 +19,8 @@ object RegionType {
 // A non-empty half-open range; [start, end)
 case class IdRange(start: Int, end: Int)
 {
-  require (start >= 0)
-  require (start < end) // not empty
+  require (start >= 0, s"Ids cannot be negative, but got: $start.")
+  require (start < end, "Id ranges cannot be empty.")
 
   // This is a strict partial ordering
   def <(x: IdRange) = end <= x.start
@@ -48,11 +48,11 @@ case class TransferSizes(min: Int, max: Int)
 {
   def this(x: Int) = this(x, x)
 
-  require (min <= max)
-  require (min >= 0 && max >= 0)
-  require (max == 0 || isPow2(max))
-  require (min == 0 || isPow2(min))
-  require (max == 0 || min != 0) // 0 is forbidden unless (0,0)
+  require (min <= max, s"Min transfer $min > max transfer $max")
+  require (min >= 0 && max >= 0, s"TransferSizes must be positive, got: ($min, $max)")
+  require (max == 0 || isPow2(max), s"TransferSizes must be a power of 2, got: $max")
+  require (min == 0 || isPow2(min), s"TransferSizes must be a power of 2, got: $min")
+  require (max == 0 || min != 0, s"TransferSize 0 is forbidden unless (0,0), got: ($min, $max)")
 
   def none = min == 0
   def contains(x: Int) = isPow2(x) && min <= x && x <= max
@@ -81,8 +81,8 @@ case class AddressRange(base: BigInt, size: BigInt) extends Ordered[AddressRange
 {
   val end = base + size
 
-  require (base >= 0)
-  require (size > 0)
+  require (base >= 0, s"AddressRange base must be positive, got: $base")
+  require (size > 0, s"AddressRange size must be > 0, got: $size")
 
   def compare(x: AddressRange) = {
     val primary   = (this.base - x.base).signum
@@ -109,8 +109,8 @@ case class AddressRange(base: BigInt, size: BigInt) extends Ordered[AddressRange
 case class AddressSet(base: BigInt, mask: BigInt) extends Ordered[AddressSet]
 {
   // Forbid misaligned base address (and empty sets)
-  require ((base & mask) == 0)
-  require (base >= 0) // TL2 address widths are not fixed => negative is ambiguous
+  require ((base & mask) == 0, s"Mis-aligned AddressSets are forbidden, got: ($base, $mask)")
+  require (base >= 0, s"AddressSet negative base is ambiguous: $base") // TL2 address widths are not fixed => negative is ambiguous
   // We do allow negative mask (=> ignore all high bits)
 
   def contains(x: BigInt) = ((x ^ base) & ~mask) == 0
diff --git a/src/main/scala/uncore/tilelink2/Xbar.scala b/src/main/scala/uncore/tilelink2/Xbar.scala
index e9746f42..7d122b3b 100644
--- a/src/main/scala/uncore/tilelink2/Xbar.scala
+++ b/src/main/scala/uncore/tilelink2/Xbar.scala
@@ -40,8 +40,8 @@ class TLXbar(policy: TLArbiter.Policy = TLArbiter.lowestIndexFirst)(implicit p:
     numClientPorts  = 1 to 32,
     numManagerPorts = 1 to 32,
     clientFn  = { seq =>
-      // An unsafe atomic port can not be combined with any other!
-      require (!seq.exists(_.unsafeAtomics) || seq.size == 1)
+      require (!seq.exists(_.unsafeAtomics) || seq.size == 1,
+        "An unsafe atomic port can not be combined with any other!")
       seq(0).copy(
         minLatency = seq.map(_.minLatency).min,
         clients = (mapInputIds(seq) zip seq) flatMap { case (range, port) =>
@@ -58,8 +58,8 @@ class TLXbar(policy: TLArbiter.Policy = TLArbiter.lowestIndexFirst)(implicit p:
         minLatency = seq.map(_.minLatency).min,
         endSinkId = outputIdRanges.map(_.map(_.end).getOrElse(0)).max,
         managers = ManagerUnification(seq.flatMap { port =>
-          // println(s"${port.managers.map(_.name)} ${port.beatBytes} vs ${seq(0).managers.map(_.name)} ${seq(0).beatBytes}")
-          require (port.beatBytes == seq(0).beatBytes)
+          require (port.beatBytes == seq(0).beatBytes,
+            s"Xbar data widths don't match: ${port.managers.map(_.name)} has ${port.beatBytes}B vs ${seq(0).managers.map(_.name)} has ${seq(0).beatBytes}B")
           val fifoIdMapper = fifoIdFactory()
           port.managers map { manager => manager.copy(
             fifoId = manager.fifoId.map(fifoIdMapper(_))