diff --git a/sbt-bridge/test/xsbt/CompileProgressSpecification.scala b/sbt-bridge/test/xsbt/CompileProgressSpecification.scala
index 2297f8bb441e..32b4f58effdb 100644
--- a/sbt-bridge/test/xsbt/CompileProgressSpecification.scala
+++ b/sbt-bridge/test/xsbt/CompileProgressSpecification.scala
@@ -8,6 +8,30 @@ import org.junit.Assert._
  */
 class CompileProgressSpecification {
 
+  @Test
+  def totalIsMoreWhenSourcePath = {
+    val srcA = """class A"""
+    val srcB = """class B"""
+    val extraC = """trait C""" // will only exist in the `-sourcepath`, causing a late compile
+    val extraD = """trait D""" // will only exist in the `-sourcepath`, causing a late compile
+    val srcE = """class E extends C""" // depends on class in the sourcepath
+    val srcF = """class F extends C, D""" // depends on classes in the sourcepath
+
+    val compilerForTesting = new ScalaCompilerForUnitTesting
+
+    val totalA = compilerForTesting.extractTotal(srcA)()
+    assertTrue("expected more than 1 unit of work for a single file", totalA > 1)
+
+    val totalB = compilerForTesting.extractTotal(srcA, srcB)()
+    assertEquals("expected twice the work for two sources", totalA * 2, totalB)
+
+    val totalC = compilerForTesting.extractTotal(srcA, srcE)(extraC)
+    assertEquals("expected 2x+1 the work for two sources, and 1 late compile", totalA * 2 + 1, totalC)
+
+    val totalD = compilerForTesting.extractTotal(srcA, srcF)(extraC, extraD)
+    assertEquals("expected 2x+2 the work for two sources, and 2 late compiles", totalA * 2 + 2, totalD)
+  }
+
   @Test
   def multipleFilesVisitSamePhases = {
     val srcA = """class A"""
diff --git a/sbt-bridge/test/xsbt/ScalaCompilerForUnitTesting.scala b/sbt-bridge/test/xsbt/ScalaCompilerForUnitTesting.scala
index 520b7f7053da..87bc45744e21 100644
--- a/sbt-bridge/test/xsbt/ScalaCompilerForUnitTesting.scala
+++ b/sbt-bridge/test/xsbt/ScalaCompilerForUnitTesting.scala
@@ -30,6 +30,12 @@ class ScalaCompilerForUnitTesting {
     tempSrcFiles.map(src => run.unitPhases(src.id))
   }
 
+  def extractTotal(srcs: String*)(extraSourcePath: String*): Int = {
+    val (tempSrcFiles, Callbacks(_, testProgress)) = compileSrcs(List(srcs.toList), extraSourcePath.toList)
+    val run = testProgress.runs.head
+    run.total
+  }
+
   def extractProgressPhases(srcs: String*): List[String] = {
     val (_, Callbacks(_, testProgress)) = compileSrcs(srcs: _*)
     testProgress.runs.head.phases
@@ -136,7 +142,7 @@ class ScalaCompilerForUnitTesting {
    * The sequence of temporary files corresponding to passed snippets and analysis
    * callback is returned as a result.
    */
-  def compileSrcs(groupedSrcs: List[List[String]]): (Seq[VirtualFile], Callbacks) = {
+  def compileSrcs(groupedSrcs: List[List[String]], sourcePath: List[String] = Nil): (Seq[VirtualFile], Callbacks) = {
       val temp = IO.createTemporaryDirectory
       val analysisCallback = new TestCallback
       val testProgress = new TestCompileProgress
@@ -146,6 +152,11 @@ class ScalaCompilerForUnitTesting {
       val bridge = new CompilerBridge
 
       val files = for ((compilationUnits, unitId) <- groupedSrcs.zipWithIndex) yield {
+        val extraFiles = sourcePath.toSeq.zipWithIndex.map {
+          case (src, i) =>
+            val fileName = s"Extra-$unitId-$i.scala"
+            prepareSrcFile(temp, fileName, src)
+        }
         val srcFiles = compilationUnits.toSeq.zipWithIndex.map {
           (src, i) =>
             val fileName = s"Test-$unitId-$i.scala"
@@ -157,10 +168,12 @@ class ScalaCompilerForUnitTesting {
         val output = new SingleOutput:
           def getOutputDirectory() = classesDir
 
+        val maybeSourcePath = if extraFiles.isEmpty then Nil else List("-sourcepath", temp.getAbsolutePath.toString)
+
         bridge.run(
           virtualSrcFiles,
           new TestDependencyChanges,
-          Array("-Yforce-sbt-phases", "-classpath", classesDirPath, "-usejavacp", "-d", classesDirPath),
+          Array("-Yforce-sbt-phases", "-classpath", classesDirPath, "-usejavacp", "-d", classesDirPath) ++ maybeSourcePath,
           output,
           analysisCallback,
           new TestReporter,
diff --git a/sbt-bridge/test/xsbti/TestCompileProgress.scala b/sbt-bridge/test/xsbti/TestCompileProgress.scala
index 9753a6e15b4c..d5dc81dfda24 100644
--- a/sbt-bridge/test/xsbti/TestCompileProgress.scala
+++ b/sbt-bridge/test/xsbti/TestCompileProgress.scala
@@ -8,9 +8,11 @@ class TestCompileProgress extends CompileProgress:
   class Run:
     private[TestCompileProgress] val _phases: mutable.Set[String] = mutable.LinkedHashSet.empty
     private[TestCompileProgress] val _unitPhases: mutable.Map[String, mutable.Set[String]] = mutable.LinkedHashMap.empty
+    private[TestCompileProgress] var _latestTotal: Int = 0
 
     def phases: List[String] = _phases.toList
     def unitPhases: collection.MapView[String, List[String]] = _unitPhases.view.mapValues(_.toList)
+    def total: Int = _latestTotal
 
   private val _runs: mutable.ListBuffer[Run] = mutable.ListBuffer.empty
   private var _currentRun: Run = new Run
@@ -27,4 +29,5 @@ class TestCompileProgress extends CompileProgress:
   override def advance(current: Int, total: Int, prevPhase: String, nextPhase: String): Boolean =
     _currentRun._phases += prevPhase
     _currentRun._phases += nextPhase
+    _currentRun._latestTotal = total
     true