diff --git a/src/main/scala/tilelink/Coalescing.scala b/src/main/scala/tilelink/Coalescing.scala
index fb0aef0..72a6fb1 100644
--- a/src/main/scala/tilelink/Coalescing.scala
+++ b/src/main/scala/tilelink/Coalescing.scala
@@ -996,7 +996,7 @@ class MemTraceDriver(config: CoalescerConfig, filename: String)(implicit
     val clientParam = Seq(
       TLMasterParameters.v1(
         name = "MemTraceDriver" + i.toString,
-        sourceId = IdRange(0, 0x100)
+        sourceId = IdRange(0, config.numOldSrcIds)
         // visibility = Seq(AddressSet(0x0000, 0xffffff))
       )
     )