diff --git a/src/main/scala/junctions/addrmap.scala b/src/main/scala/junctions/addrmap.scala
index 19613ae7..275e4ff3 100644
--- a/src/main/scala/junctions/addrmap.scala
+++ b/src/main/scala/junctions/addrmap.scala
@@ -125,7 +125,7 @@ class AddrMap(
       val brEnd = br.start + br.size
       val abOverlaps = ar.start < brEnd && br.start < arEnd
       require(!abOverlaps,
-        "region $an@0x${ar.start.toString(16)} overlaps region $bn@0x${br.start.toString(16)}")
+        s"region $an@0x${ar.start.toString(16)} overlaps region $bn@0x${br.start.toString(16)}")
   }
 
   def toRange: MemRange = MemRange(start, size, attr)