diff --git a/compile/inc/src/main/scala/sbt/inc/ClassfileManager.scala b/compile/inc/src/main/scala/sbt/inc/ClassfileManager.scala
index 636c0aec36..e4a449a4e9 100644
--- a/compile/inc/src/main/scala/sbt/inc/ClassfileManager.scala
+++ b/compile/inc/src/main/scala/sbt/inc/ClassfileManager.scala
@@ -13,7 +13,7 @@ trait ClassfileManager
 	* Any empty ancestor directories of deleted files must not exist either.*/
 	def delete(classes: Iterable[File]): Unit
 
-	/** Called once per compilation step with the class files generated during that step.*/	
+	/** Called once per compilation step with the class files generated during that step.*/
 	def generated(classes: Iterable[File]): Unit
 
 	/** Called once at the end of the whole compilation run, with `success` indicating whether compilation succeeded (true) or not (false).*/
@@ -29,29 +29,45 @@ object ClassfileManager
 		def generated(classes: Iterable[File]) {}
 		def complete(success: Boolean) {}
 	}
+	@deprecated("Use overloaded variant that takes additional logger argument, instead.", "0.13.5")
+	def transactional(tempDir0: File): () => ClassfileManager =
+		transactional(tempDir0, sbt.Logger.Null)
 	/** When compilation fails, this ClassfileManager restores class files to the way they were before compilation.*/
-	def transactional(tempDir0: File): () => ClassfileManager = () => new ClassfileManager
+	def transactional(tempDir0: File, logger: sbt.Logger): () => ClassfileManager = () => new ClassfileManager
 	{
 		val tempDir = tempDir0.getCanonicalFile
 		IO.delete(tempDir)
 		IO.createDirectory(tempDir)
+		logger.debug(s"Created transactional ClassfileManager with tempDir = $tempDir")
 
 		private[this] val generatedClasses = new mutable.HashSet[File]
 		private[this] val movedClasses = new mutable.HashMap[File, File]
-	
+
+		private def showFiles(files: Iterable[File]): String = files.map(f => s"\t$f").mkString("\n")
 		def delete(classes: Iterable[File])
 		{
-			for(c <- classes) if(c.exists && !movedClasses.contains(c) && !generatedClasses(c))
+			logger.debug(s"About to delete class files:\n${showFiles(classes)}")
+			val toBeBackedUp = classes.filter(c => c.exists && !movedClasses.contains(c) && !generatedClasses(c))
+			logger.debug(s"We backup classs files:\n${showFiles(toBeBackedUp)}")
+			for(c <- toBeBackedUp) {
 				movedClasses.put(c, move(c))
+			}
 			IO.deleteFilesEmptyDirs(classes)
 		}
-		def generated(classes: Iterable[File]): Unit = generatedClasses ++= classes
+		def generated(classes: Iterable[File]): Unit = {
+			logger.debug(s"Registering generated classes:\n${showFiles(classes)}")
+			generatedClasses ++= classes
+		}
 		def complete(success: Boolean)
 		{
 			if(!success) {
+				logger.debug("Rolling back changes to class files.")
+				logger.debug(s"Removing generated classes:\n${showFiles(generatedClasses)}")
 				IO.deleteFilesEmptyDirs(generatedClasses)
+				logger.debug(s"Restoring class files: \n${showFiles(movedClasses.map(_._1))}")
 				for( (orig, tmp) <- movedClasses ) IO.move(tmp, orig)
 			}
+			logger.debug(s"Removing the temporary directory used for backing up class files: $tempDir")
 			IO.delete(tempDir)
 		}
 
diff --git a/compile/inc/src/main/scala/sbt/inc/IncOptions.scala b/compile/inc/src/main/scala/sbt/inc/IncOptions.scala
index 0e634aa4fc..70add51834 100644
--- a/compile/inc/src/main/scala/sbt/inc/IncOptions.scala
+++ b/compile/inc/src/main/scala/sbt/inc/IncOptions.scala
@@ -234,9 +234,12 @@ object IncOptions extends Serializable {
     private def readResolve(): Object = IncOptions
 	//- EXPANDED CASE CLASS METHOD END -//
 
-	def defaultTransactional(tempDir: File): IncOptions = setTransactional(Default, tempDir)
+	@deprecated("Use IncOptions.Default.withNewClassfileManager(ClassfileManager.transactional(tempDir)), instead.", "0.13.5")
+	def defaultTransactional(tempDir: File): IncOptions =
+		setTransactional(Default, tempDir)
+	@deprecated("Use opts.withNewClassfileManager(ClassfileManager.transactional(tempDir)), instead.", "0.13.5")
 	def setTransactional(opts: IncOptions, tempDir: File): IncOptions =
-		opts.copy(newClassfileManager = ClassfileManager.transactional(tempDir))
+		opts.withNewClassfileManager(ClassfileManager.transactional(tempDir, sbt.Logger.Null))
 
 	private val transitiveStepKey       = "transitiveStep"
 	private val recompileAllFractionKey = "recompileAllFraction"
diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index 96390d8692..d240104679 100755
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -215,7 +215,8 @@ object Defaults extends BuildCommon
 	)
 
 	def compileBase = inTask(console)(compilersSetting :: Nil) ++ compileBaseGlobal ++ Seq(
-		incOptions := IncOptions.setTransactional(incOptions.value, crossTarget.value / "classes.bak"),
+		incOptions := incOptions.value.withNewClassfileManager(
+			sbt.inc.ClassfileManager.transactional(crossTarget.value / "classes.bak", sbt.Logger.Null)),
 		scalaInstance <<= scalaInstanceTask,
 		crossVersion := (if(crossPaths.value) CrossVersion.binary else CrossVersion.Disabled),
 		crossTarget := makeCrossTarget(target.value, scalaBinaryVersion.value, sbtBinaryVersion.value, sbtPlugin.value, crossPaths.value)