diff --git a/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala b/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala
index 4e2abdbe8..831902d55 100644
--- a/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala
+++ b/main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala
@@ -661,7 +661,7 @@ object BuildServerProtocol {
     val target = Keys.bspTargetIdentifier.value
     val classpath = Keys.fullClasspath.value.map(_.data.toURI).toVector
     val jvmOptions = Keys.javaOptions.value.toVector
-    val baseDir = Keys.baseDirectory.value.toURI().toString()
+    val baseDir = Keys.baseDirectory.value.getAbsolutePath
     val env = envVars.value
 
     JvmEnvironmentItem(
diff --git a/server-test/src/test/scala/testpkg/BuildServerTest.scala b/server-test/src/test/scala/testpkg/BuildServerTest.scala
index 1b8fd06fb..da4659fe1 100644
--- a/server-test/src/test/scala/testpkg/BuildServerTest.scala
+++ b/server-test/src/test/scala/testpkg/BuildServerTest.scala
@@ -412,7 +412,7 @@ object BuildServerTest extends AbstractServerTest {
         (s contains "jsoniter-scala-core_2.13-2.13.11.jar") && // compile dependency
         (s contains "\"jvmOptions\":[\"Xmx256M\"]") &&
         (s contains "\"environmentVariables\":{\"KEY\":\"VALUE\"}") &&
-        (s contains "/buildserver/run-and-test/") // working directory
+        (s contains s""""workingDirectory":"${svr.baseDirectory.getAbsolutePath}/run-and-test"""")
       }
     }
   }
@@ -434,7 +434,8 @@ object BuildServerTest extends AbstractServerTest {
         (s contains "jsoniter-scala-core_2.13-2.13.11.jar") && // compile dependency
         (s contains "scalatest_2.13-3.0.8.jar") && // test dependency
         (s contains "\"jvmOptions\":[\"Xmx512M\"]") &&
-        (s contains "\"environmentVariables\":{\"KEY_TEST\":\"VALUE_TEST\"}")
+        (s contains "\"environmentVariables\":{\"KEY_TEST\":\"VALUE_TEST\"}") &&
+        (s contains s""""workingDirectory":"${svr.baseDirectory.getAbsolutePath}/run-and-test"""")
       }
     }
   }