diff --git a/luna/src/main/java/org/classdump/luna/lib/StringLib.java b/luna/src/main/java/org/classdump/luna/lib/StringLib.java
index e57514f7..b4f7e7f6 100644
--- a/luna/src/main/java/org/classdump/luna/lib/StringLib.java
+++ b/luna/src/main/java/org/classdump/luna/lib/StringLib.java
@@ -1344,7 +1344,7 @@ public final class StringLib {
         }
       } while (idx >= 0);
 
-      context.getReturnBuffer().setTo(bld.toString());
+      context.getReturnBuffer().setTo(ByteString.of(bld.toString()));
     }
 
     private static class SuspendedState {