1 files changed, 6 insertions, 3 deletions
diff --git a/kamon-core/src/main/scala/kamon/trace/SpanContext.scala b/kamon-core/src/main/scala/kamon/trace/SpanContext.scala
index 7f5962e0..a3afb36d 100644
--- a/kamon-core/src/main/scala/kamon/trace/SpanContext.scala
+++ b/kamon-core/src/main/scala/kamon/trace/SpanContext.scala
@@ -1,4 +1,5 @@
 package kamon.trace
+
 import java.lang
 import java.util.Map
 import scala.collection.JavaConverters._
@@ -6,16 +7,18 @@ import scala.collection.JavaConverters._
 class SpanContext(val traceID: Long, val spanID: Long, val parentID: Long) extends io.opentracing.SpanContext {
   private var baggage = scala.collection.immutable.Map.empty[String, String]
 
-  private[kamon] def addBaggageItem(key: String, value: String): Unit = {
+  private[kamon] def addBaggageItem(key: String, value: String): Unit = synchronized {
     baggage = baggage + (key -> value)
   }
 
-  private[kamon] def getBaggage(key: String): String =
+  private[kamon] def getBaggage(key: String): String = synchronized {
     baggage.get(key).getOrElse(null)
+  }
 
   private[kamon] def baggageMap: scala.collection.immutable.Map[String, String] =
     baggage
 
-  override def baggageItems(): lang.Iterable[Map.Entry[String, String]] =
+  override def baggageItems(): lang.Iterable[Map.Entry[String, String]] = synchronized {
     baggage.asJava.entrySet()
+  }
 }