diff --git a/compile/inc/Locate.scala b/compile/inc/Locate.scala
index 08eaeed82..7e35c8e02 100644
--- a/compile/inc/Locate.scala
+++ b/compile/inc/Locate.scala
@@ -50,7 +50,7 @@ object Locate
 	def definesClass(entry: File): String => Boolean =
 		if(entry.isDirectory)
 			directoryDefinesClass(entry)
-		else if(entry.exists)
+		else if(entry.exists && classpath.ClasspathUtilities.isArchive(entry))
 			jarDefinesClass(entry)
 		else
 			const(false)
diff --git a/project/Sbt.scala b/project/Sbt.scala
index 91008ded3..65d891058 100644
--- a/project/Sbt.scala
+++ b/project/Sbt.scala
@@ -90,7 +90,7 @@ object Sbt extends Build
 
 		// Implements the core functionality of detecting and propagating changes incrementally.
 		//   Defines the data structures for representing file fingerprints and relationships and the overall source analysis
-	lazy val compileIncrementalSub = testedBaseProject(compilePath / "inc", "Incremental Compiler") dependsOn(collectionSub, apiSub, ioSub, logSub)
+	lazy val compileIncrementalSub = testedBaseProject(compilePath / "inc", "Incremental Compiler") dependsOn(collectionSub, apiSub, ioSub, logSub, classpathSub)
 		// Persists the incremental data structures using SBinary
 	lazy val compilePersistSub = baseProject(compilePath / "persist", "Persist") dependsOn(compileIncrementalSub, apiSub) settings(sbinary)
 		// sbt-side interface to compiler.  Calls compiler-side interface reflectively