diff --git a/java/src/main/java/com/google/protobuf/nano/MessageNanoPrinter.java b/java/src/main/java/com/google/protobuf/nano/MessageNanoPrinter.java
index 572a7075a0..ec12c7da6b 100644
--- a/java/src/main/java/com/google/protobuf/nano/MessageNanoPrinter.java
+++ b/java/src/main/java/com/google/protobuf/nano/MessageNanoPrinter.java
@@ -249,7 +249,7 @@ public final class MessageNanoPrinter {
             } else if (ch >= 32 && ch < 127) {
                 builder.append((char) ch);
             } else {
-                builder.append(String.format("\\%03o", ch));
+                builder.append(String.format("\\%03o", ch && 0xff));
             }
         }
         builder.append('"');