diff --git a/main/actions/ForkTests.scala b/main/actions/ForkTests.scala
index b47319aba..4aee621bd 100755
--- a/main/actions/ForkTests.scala
+++ b/main/actions/ForkTests.scala
@@ -27,8 +27,7 @@ private[sbt] object ForkTests {
 		}
 		val argMap = frameworks.map {
 			f => f.implClassName -> opts.flatMap {
-				case Argument(None, args) =>  args
-				case Argument(Some(`f`), args) => args
+				case Argument(None | Some(`f`), args) => args
 				case _ => Nil
 			}
 		}.toMap
@@ -112,4 +111,4 @@ private final class React(is: ObjectInputStream, os: ObjectOutputStream, log: Lo
 			listeners.foreach(_ endGroup (group, result))
 			react()
 	}
-}
\ No newline at end of file
+}
diff --git a/sbt/src/sbt-test/tests/t543/project/Ticket543Test.scala b/sbt/src/sbt-test/tests/t543/project/Ticket543Test.scala
index dfad98959..26e7903fc 100755
--- a/sbt/src/sbt-test/tests/t543/project/Ticket543Test.scala
+++ b/sbt/src/sbt-test/tests/t543/project/Ticket543Test.scala
@@ -2,19 +2,23 @@ import sbt._
 import Keys._
 import Tests._
 import Defaults._
+import java.io.{ CharArrayWriter, PrintWriter }
 
 object Ticket543Test extends Build {
 	val marker = new File("marker")
-	val check = TaskKey[Unit]("check", "Check non-null error has been returned.")
+	val check = TaskKey[Unit]("check", "Check correct error has been returned.")
 
 	lazy val root = Project("root", file("."), settings = defaultSettings ++  Seq(
 		libraryDependencies += "org.scalatest" %% "scalatest" % "1.8" % "test",
 		fork := true,
 		testListeners += new TestReportListener {
 		  def testEvent(event: TestEvent) {
-				for (e <- event.detail.filter(_.result() == org.scalatools.testing.Result.Failure)) {
-					if (e.error() ne null) {
-						marker.createNewFile()
+				for (e <- event.detail.filter(_.result == org.scalatools.testing.Result.Failure)) {
+					if (e.error ne null) {
+						val caw = new CharArrayWriter
+						e.error.printStackTrace(new PrintWriter(caw))
+						if (caw.toString.contains("Test.scala:"))
+							marker.createNewFile()
 					}
 				}
 		  }
@@ -25,7 +29,7 @@ object Ticket543Test extends Build {
 		check := {
 			val exists = marker.exists
 			marker.delete()
-			if (!exists) error("Null error had been returned previously")
+			if (!exists) error("Null or invalid error had been returned previously")
 		}
 	))
 }
diff --git a/testing/agent/src/main/java/sbt/ForkMain.java b/testing/agent/src/main/java/sbt/ForkMain.java
index 271c873f5..2fe088a49 100755
--- a/testing/agent/src/main/java/sbt/ForkMain.java
+++ b/testing/agent/src/main/java/sbt/ForkMain.java
@@ -48,17 +48,15 @@ public class ForkMain {
 			}
 		}
 	}
-	static class ForkError extends Exception implements Serializable {
+	static class ForkError extends Exception {
 		private String originalMessage;
-		private StackTraceElement[] originalStackTrace;
 		private ForkError cause;
 		ForkError(Throwable t) {
 			originalMessage = t.getMessage();
-			originalStackTrace = t.getStackTrace();
+			setStackTrace(t.getStackTrace());
 			if (t.getCause() != null) cause = new ForkError(t.getCause());
 		}
 		public String getMessage() { return originalMessage; }
-		public StackTraceElement[] getStackTrace() { return originalStackTrace; }
 		public Exception getCause() { return cause; }
 	}
 	static class ForkEvent implements Event, Serializable {