diff --git a/main/ClasspathProject.scala b/main/ClasspathProject.scala
index 352cb8fca..8d8ac08e4 100644
--- a/main/ClasspathProject.scala
+++ b/main/ClasspathProject.scala
@@ -140,10 +140,11 @@ object ClasspathProject
 	}
 
 	def parseSimpleConfigurations(confString: String): Map[String, String] =
-		confString.split(";").map(
-			_.split("->",2).toList.map(_.trim) match {
+		confString.split(";").map( conf =>
+			conf.split("->",2).toList.map(_.trim) match {
 				case x :: Nil => (x,x)
 				case x :: y :: Nil => (x,y)
+				case _ => error("Invalid configuration '" + conf + "'") // shouldn't get here
 			}
 		).toMap
 }
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