diff --git a/README.md b/README.md
index 69bacec..66d6549 100644
--- a/README.md
+++ b/README.md
@@ -527,9 +527,9 @@ The code has been updated to support compiler:
 
 ```bash
 $ moon version --all
-moon 0.1.20241106 (79e45ae 2024-11-06) ~/.moon/bin/moon
-moonc v0.1.20241106+8f17a3fc7 ~/.moon/bin/moonc
-moonrun 0.1.20241106 (79e45ae 2024-11-06) ~/.moon/bin/moonrun
+moon 0.1.20241111 (e6d64e0 2024-11-11) ~/.moon/bin/moon
+moonc v0.1.20241111+dc2407357 ~/.moon/bin/moonc
+moonrun 0.1.20241111 (e6d64e0 2024-11-11) ~/.moon/bin/moonrun
 ```
 
 Use `moonup` to manage `moon` compiler versions:
diff --git a/moon.mod.json b/moon.mod.json
index 90a9735..f4993f5 100644
--- a/moon.mod.json
+++ b/moon.mod.json
@@ -1,6 +1,6 @@
 {
   "name": "extism/moonbit-pdk",
-  "version": "0.41.0",
+  "version": "0.42.0",
   "deps": {},
   "readme": "README.md",
   "repository": "https://github.com/extism/moonbit-pdk",
diff --git a/pdk/string.mbt b/pdk/string.mbt
index f9cbe87..b5e59d0 100644
--- a/pdk/string.mbt
+++ b/pdk/string.mbt
@@ -1,7 +1,7 @@
 /// ToUtf8 is a workaround since the standard library does not make
 /// it easy to write a standard UTF-8 string.
 /// https://github.com/moonbitlang/core/issues/484
-pub trait ToUtf8 {
+pub(open) trait ToUtf8 {
   to_utf8(Self) -> Bytes
 }
 
@@ -23,7 +23,7 @@ pub impl ToUtf8 for String with to_utf8(s : String) -> Bytes {
 /// ToUtf16 is a workaround since the standard library does not make
 /// it easy to write a standard UTF-16 string from UTF-8.
 /// https://github.com/moonbitlang/core/issues/484
-pub trait ToUtf16 {
+pub(open) trait ToUtf16 {
   to_utf16(Self) -> String
 }