diff --git a/build.sbt b/build.sbt
index f313fb9fe..8de457067 100644
--- a/build.sbt
+++ b/build.sbt
@@ -214,6 +214,11 @@ lazy val testingProj = (project in file("testing"))
     sourceManaged in (Compile, generateContrabands) := baseDirectory.value / "src" / "main" / "contraband-scala",
     contrabandFormatsForType in generateContrabands in Compile := ContrabandConfig.getFormats,
     mimaSettings,
+    mimaBinaryIssueFilters ++= Seq(
+      // private[sbt]
+      ProblemFilters.exclude[IncompatibleMethTypeProblem]("sbt.TestStatus.write"),
+      ProblemFilters.exclude[IncompatibleResultTypeProblem]("sbt.TestStatus.read"),
+    ),
   )
   .configure(addSbtIO, addSbtCompilerClasspath, addSbtUtilLogging)
 
diff --git a/main-command/src/main/scala/sbt/internal/server/Server.scala b/main-command/src/main/scala/sbt/internal/server/Server.scala
index 261e63336..95ef32c95 100644
--- a/main-command/src/main/scala/sbt/internal/server/Server.scala
+++ b/main-command/src/main/scala/sbt/internal/server/Server.scala
@@ -63,7 +63,8 @@ private[sbt] object Server {
                 val maxSocketLength = new UnixDomainSocketLibrary.SockaddrUn().sunPath.length - 1
                 val path = socketfile.getAbsolutePath
                 if (path.length > maxSocketLength)
-                  sys.error("socket file absolute path too long; " +
+                  sys.error(
+                    "socket file absolute path too long; " +
                       "either switch to another connection type " +
                       "or define a short \"SBT_GLOBAL_SERVER_DIR\" value. " +
                       s"Current path: ${path}")
diff --git a/testing/src/main/scala/sbt/TestStatusReporter.scala b/testing/src/main/scala/sbt/TestStatusReporter.scala
index ab248741f..af5d84465 100644
--- a/testing/src/main/scala/sbt/TestStatusReporter.scala
+++ b/testing/src/main/scala/sbt/TestStatusReporter.scala
@@ -8,14 +8,16 @@
 package sbt
 
 import java.io.File
-import sbt.io.IO
 
-import scala.collection.mutable.Map
+import sbt.io.IO
 import sbt.protocol.testing.TestResult
+import java.util.concurrent.ConcurrentHashMap
+
+import scala.collection.concurrent
 
 // Assumes exclusive ownership of the file.
 private[sbt] class TestStatusReporter(f: File) extends TestsListener {
-  private lazy val succeeded = TestStatus.read(f)
+  private lazy val succeeded: concurrent.Map[String, Long] = TestStatus.read(f)
 
   def doInit = ()
   def startGroup(name: String): Unit = { succeeded remove name; () }
@@ -32,13 +34,16 @@ private[sbt] class TestStatusReporter(f: File) extends TestsListener {
 
 private[sbt] object TestStatus {
   import java.util.Properties
-  def read(f: File): Map[String, Long] = {
+  def read(f: File): concurrent.Map[String, Long] = {
     import scala.collection.JavaConverters._
     val properties = new Properties
     IO.load(properties, f)
-    properties.asScala map { case (k, v) => (k, v.toLong) }
+    val result = new ConcurrentHashMap[String, Long]()
+    properties.asScala.iterator.foreach { case (k, v) => result.put(k, v.toLong) }
+    result.asScala
   }
-  def write(map: Map[String, Long], label: String, f: File): Unit = {
+
+  def write(map: collection.Map[String, Long], label: String, f: File): Unit = {
     val properties = new Properties
     for ((test, lastSuccessTime) <- map)
       properties.setProperty(test, lastSuccessTime.toString)