diff --git a/build.sbt b/build.sbt
index 9f52114a8..1b300700a 100644
--- a/build.sbt
+++ b/build.sbt
@@ -10,7 +10,7 @@ inThisBuild(
   )
 )
 
-val scalalibVersion = "11.2.9"
+val scalalibVersion = "11.3.0"
 
 val commonSettings = Seq(
   scalacOptions := Seq(
diff --git a/core/src/main/scala/Timestamp.scala b/core/src/main/scala/Timestamp.scala
index 89fbfb8a1..c7d006455 100644
--- a/core/src/main/scala/Timestamp.scala
+++ b/core/src/main/scala/Timestamp.scala
@@ -3,12 +3,12 @@ package chess
 opaque type Timestamp = Long
 object Timestamp extends OpaqueLong[Timestamp]:
   extension (t: Timestamp)
-    def -(o: Timestamp): Centis = Centis.ofMillis(t - o.value)
-    def +(o: Centis): Timestamp = Timestamp(t + o.millis)
+    def --(o: Timestamp): Centis = Centis.ofMillis(t - o.value)
+    def +(o: Centis): Timestamp  = Timestamp(t + o.millis)
 
 trait Timestamper:
   def now: Timestamp
-  def toNow(ts: Timestamp) = now - ts
+  def toNow(ts: Timestamp) = now -- ts
 
 private[chess] object RealTimestamper extends Timestamper:
   def now = Timestamp(System.currentTimeMillis)