diff --git a/src/main/java/com/android/tools/r8/naming/ProguardMapMinifier.java b/src/main/java/com/android/tools/r8/naming/ProguardMapMinifier.java
index fab5f50..4fd6274 100644
--- a/src/main/java/com/android/tools/r8/naming/ProguardMapMinifier.java
+++ b/src/main/java/com/android/tools/r8/naming/ProguardMapMinifier.java
@@ -495,7 +495,7 @@
       DexString reservedName = getReservedName(definition, name, holder);
       if (reservedName != null) {
         if (!isAvailable.test(reservedName, reference)) {
-          reportReservationError(definition.asDexReference(), reservedName);
+          reportReservationError(definition.toReference(), reservedName);
         }
         return reservedName;
       }