diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index af1e61a5..21f150aa 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -38,7 +38,7 @@ jobs:
     - uses: actions/checkout@v3
     - uses: actions-rs/toolchain@v1
       with:
-        toolchain: nightly-2023-04-20
+        toolchain: nightly-2023-06-01
         components: cargo, clippy, rustfmt
     - run: rustc -vV
     - run: cargo build
diff --git a/.github/workflows/rust_bors.yml b/.github/workflows/rust_bors.yml
index 6f000cd5..3eac15db 100644
--- a/.github/workflows/rust_bors.yml
+++ b/.github/workflows/rust_bors.yml
@@ -27,7 +27,7 @@ jobs:
     - uses: actions/checkout@v3
     - uses: actions-rs/toolchain@v1
       with:
-          toolchain: nightly-2023-04-20
+          toolchain: nightly-2023-06-01
           components: cargo, clippy, rustfmt
     - run: rustc -vV
     - run: cargo build
diff --git a/Cargo.toml b/Cargo.toml
index ecc7fc1c..b994fc27 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,6 +7,7 @@ members = [
     # This is needed for rust-analyzer, uitests and other tools
     "marker_lints",
 ]
+resolver = "2"
 
 [workspace.metadata.marker.lints]
 marker_lints = { path = "marker_lints" }
diff --git a/cargo-marker/src/driver.rs b/cargo-marker/src/driver.rs
index 4708d1bb..b5136625 100644
--- a/cargo-marker/src/driver.rs
+++ b/cargo-marker/src/driver.rs
@@ -21,7 +21,7 @@ use crate::{cli::Flags, ExitStatus};
 /// This is the driver version and toolchain, that is used by the setup command
 /// to install the driver.
 static DEFAULT_DRIVER_INFO: Lazy<RustcDriverInfo> = Lazy::new(|| RustcDriverInfo {
-    toolchain: "nightly-2023-04-20".to_string(),
+    toolchain: "nightly-2023-06-01".to_string(),
     version: "0.1.0".to_string(),
     api_version: "0.1.0".to_string(),
 });
diff --git a/marker_driver_rustc/src/context.rs b/marker_driver_rustc/src/context.rs
index ff0915c3..c837bb89 100644
--- a/marker_driver_rustc/src/context.rs
+++ b/marker_driver_rustc/src/context.rs
@@ -88,27 +88,27 @@ impl<'ast, 'tcx: 'ast> DriverContext<'ast> for RustcContext<'ast, 'tcx> {
             lint,
             id,
             self.rustc_converter.to_span(diag.span),
-            diag.msg(),
+            diag.msg().to_string(),
             |builder| {
                 for part in diag.parts.get() {
                     match part {
                         marker_api::diagnostic::DiagnosticPart::Help { msg } => {
-                            builder.help(msg.get());
+                            builder.help(msg.get().to_string());
                         },
                         marker_api::diagnostic::DiagnosticPart::HelpSpan { msg, span } => {
-                            builder.span_help(self.rustc_converter.to_span(span), msg.get());
+                            builder.span_help(self.rustc_converter.to_span(span), msg.get().to_string());
                         },
                         marker_api::diagnostic::DiagnosticPart::Note { msg } => {
-                            builder.note(msg.get());
+                            builder.note(msg.get().to_string());
                         },
                         marker_api::diagnostic::DiagnosticPart::NoteSpan { msg, span } => {
-                            builder.span_note(self.rustc_converter.to_span(span), msg.get());
+                            builder.span_note(self.rustc_converter.to_span(span), msg.get().to_string());
                         },
                         marker_api::diagnostic::DiagnosticPart::Suggestion { msg, span, sugg, app } => {
                             builder.span_suggestion(
                                 self.rustc_converter.to_span(span),
-                                msg.get(),
-                                sugg.get(),
+                                msg.get().to_string(),
+                                sugg.get().to_string(),
                                 self.rustc_converter.to_applicability(*app),
                             );
                         },
diff --git a/marker_driver_rustc/src/conversion/marker/expr.rs b/marker_driver_rustc/src/conversion/marker/expr.rs
index f25e5e25..131587e3 100644
--- a/marker_driver_rustc/src/conversion/marker/expr.rs
+++ b/marker_driver_rustc/src/conversion/marker/expr.rs
@@ -292,6 +292,10 @@ impl<'ast, 'tcx> MarkerConverterInner<'ast, 'tcx> {
                     StrLitData::Bytes(self.alloc_slice(bytes.iter().copied()).into()),
                 )
             })),
+            // Still unstable see: https://github.com/rust-lang/rust/issues/105723
+            rustc_ast::LitKind::CStr(_, _) => {
+                ExprKind::Unstable(self.alloc(UnstableExpr::new(data, ExprPrecedence::Lit)))
+            },
             rustc_ast::LitKind::Byte(value) => {
                 ExprKind::IntLit(self.alloc(IntLitExpr::new(data, u128::from(*value), None)))
             },
diff --git a/marker_driver_rustc/src/main.rs b/marker_driver_rustc/src/main.rs
index 565e75c8..9446ae92 100644
--- a/marker_driver_rustc/src/main.rs
+++ b/marker_driver_rustc/src/main.rs
@@ -40,7 +40,7 @@ use std::ops::Deref;
 use std::path::{Path, PathBuf};
 use std::process::{exit, Command};
 
-const RUSTC_TOOLCHAIN_VERSION: &str = "nightly-2023-04-20";
+const RUSTC_TOOLCHAIN_VERSION: &str = "nightly-2023-06-01";
 
 struct DefaultCallbacks;
 impl rustc_driver::Callbacks for DefaultCallbacks {}
diff --git a/rust-toolchain b/rust-toolchain
index 33a87e96..9612e9ee 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1,4 +1,4 @@
 [toolchain]
-channel = "nightly-2023-04-20"
+channel = "nightly-2023-06-01"
 components = ["cargo", "llvm-tools-preview", "rust-src", "rust-std", "rustc", "rustc-dev", "rustfmt"]
 # This has to be synced with the toolchain in `github/workflows`
diff --git a/util/update-toolchain.sh b/util/update-toolchain.sh
index 8cf33e2c..e231e712 100755
--- a/util/update-toolchain.sh
+++ b/util/update-toolchain.sh
@@ -2,7 +2,7 @@
 
 if [[ $1 == nightly-????-??-?? ]]
 then
-    sed -i "s/nightly-2023-04-20/$1/g" ./marker_driver_rustc/src/main.rs ./rust-toolchain .github/workflows/* ./util/update-toolchain.sh cargo-marker/src/driver.rs
+    sed -i "s/nightly-2023-06-01/$1/g" ./marker_driver_rustc/src/main.rs ./rust-toolchain .github/workflows/* ./util/update-toolchain.sh cargo-marker/src/driver.rs
 else
     echo "Please enter a valid toolchain like \`nightly-2022-01-01\`"
 fi;