diff --git a/main/src/main/scala/sbt/internal/LogManager.scala b/main/src/main/scala/sbt/internal/LogManager.scala
index 2bcf8de01..635f5a898 100644
--- a/main/src/main/scala/sbt/internal/LogManager.scala
+++ b/main/src/main/scala/sbt/internal/LogManager.scala
@@ -129,7 +129,11 @@ object LogManager {
 
   // This is the default implementation for the relay appender
   val defaultRelay: Unit => Appender = _ => defaultRelayImpl
-  private[this] lazy val defaultRelayImpl: RelayAppender = new RelayAppender("Relay0")
+  private[this] lazy val defaultRelayImpl: RelayAppender = {
+    val appender = new RelayAppender("Relay0")
+    appender.start()
+    appender
+  }
 
   private[this] def hasExplicitGlobalLogLevels(s: State): Boolean =
     State.getBoolean(s, BasicKeys.explicitGlobalLogLevels, default = false)
diff --git a/sbt/src/main/resources/log4j2.component.properties b/sbt/src/main/resources/log4j2.component.properties
new file mode 100644
index 000000000..ee7c90784
--- /dev/null
+++ b/sbt/src/main/resources/log4j2.component.properties
@@ -0,0 +1 @@
+Log4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector