diff --git a/compiler/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala b/compiler/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
index e4312f46f779..d745d8d20081 100644
--- a/compiler/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/UniqueMessagePositions.scala
@@ -10,7 +10,7 @@ import core.Contexts._
   * are suppressed, unless they are of increasing severity. */
 trait UniqueMessagePositions extends Reporter {
 
-  private val positions = new mutable.HashMap[(SourceFile, Int), Diagnostic]
+  private val positions = new mutable.HashMap[(SourceFile, Integer), Diagnostic]
 
   /** Logs a position and returns true if it was already logged.
    *  @note  Two positions are considered identical for logging if they have the same point.
diff --git a/sbt-bridge/src/dotty/tools/xsbt/DelegatingReporter.java b/sbt-bridge/src/dotty/tools/xsbt/DelegatingReporter.java
index 4a170af85c88..6bf161fafebf 100644
--- a/sbt-bridge/src/dotty/tools/xsbt/DelegatingReporter.java
+++ b/sbt-bridge/src/dotty/tools/xsbt/DelegatingReporter.java
@@ -3,10 +3,14 @@
  */
 package dotty.tools.xsbt;
 
+import scala.Tuple2;
+import scala.collection.mutable.HashMap;
+
 import dotty.tools.dotc.core.Contexts.Context;
 import dotty.tools.dotc.reporting.AbstractReporter;
 import dotty.tools.dotc.reporting.Diagnostic;
 import dotty.tools.dotc.reporting.Message;
+import dotty.tools.dotc.util.SourceFile;
 import dotty.tools.dotc.util.SourcePosition;
 import xsbti.Position;
 import xsbti.Severity;
@@ -62,4 +66,11 @@ private static Position positionOf(SourcePosition pos) {
       return PositionBridge.noPosition;
     }
   }
+
+  @SuppressWarnings("unchecked")
+  // [warn] sbt-bridge/src/dotty/tools/xsbt/DelegatingReporter.java:18:1: dotty$tools$dotc$reporting$UniqueMessagePositions$$positions() in dotty.tools.dotc.reporting.AbstractReporter implements dotty$tools$dotc$reporting$UniqueMessagePositions$$positions() in dotty.tools.dotc.reporting.UniqueMessagePositions
+  // [warn]   return type requires unchecked conversion from scala.collection.mutable.HashMap to scala.collection.mutable.HashMap<scala.Tuple2<dotty.tools.dotc.util.SourceFile,java.lang.Integer>,dotty.tools.dotc.reporting.Diagnostic>
+  public HashMap<Tuple2<SourceFile, Integer>, Diagnostic> dotty$tools$dotc$reporting$UniqueMessagePositions$$positions() {
+    return (HashMap<Tuple2<SourceFile, Integer>, Diagnostic>) super.dotty$tools$dotc$reporting$UniqueMessagePositions$$positions();
+  }
 }