diff --git a/main/src/main/scala/sbt/internal/server/LanguageServerReporter.scala b/main/src/main/scala/sbt/internal/server/LanguageServerReporter.scala
index ec4137480..1f8cfd290 100644
--- a/main/src/main/scala/sbt/internal/server/LanguageServerReporter.scala
+++ b/main/src/main/scala/sbt/internal/server/LanguageServerReporter.scala
@@ -51,7 +51,7 @@ class LanguageServerReporter(
     val pos = problem.position
     pos.sourceFile.toOption foreach { sourceFile: File =>
       problemsByFile.get(sourceFile) match {
-        case Some(xs: List[Problem]) => problemsByFile(sourceFile) = problem :: xs
+        case Some(xs: List[Problem]) => problemsByFile(sourceFile) = xs :+ problem
         case _                       => problemsByFile(sourceFile) = List(problem)
       }
     }