diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 114e6dc..16fa7ef 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,14 +7,14 @@ on:
 jobs:
   build-linux:
     runs-on: ubuntu-latest
-    container: swiftlang/swift:nightly-6.0-jammy
+    container: swiftlang/swift:nightly-main-jammy
     steps:
       - uses: actions/checkout@v4
       - run: apt-get update && apt-get install --no-install-recommends -y make llvm-14
       - run: make OBJCOPY=llvm-objcopy-14
   lint:
     runs-on: ubuntu-latest
-    container: swiftlang/swift:nightly-6.0-jammy
+    container: swiftlang/swift:nightly-main-jammy
     steps:
       - uses: actions/checkout@v4
       - run: swift format lint -rs .
diff --git a/README.md b/README.md
index caad115..d1cf6b1 100644
--- a/README.md
+++ b/README.md
@@ -19,12 +19,12 @@ An operating system written in Swift.
   - Fedora: `sudo dnf install qemu-system-aarch64-core`
   - Ubuntu: `sudo apt install qemu-system-arm`
   - macOS: `brew install qemu`
-- Swift 6.0 (because Embedded Swift is used)
+- Swift trunk development (main) toolchain (because Embedded Swift is used)
   - On Linux, you can easily install the toolchain using [swiftly](https://swift-server.github.io/swiftly/).
 
     ```shell
     curl -L https://swift-server.github.io/swiftly/swiftly-install.sh | bash
-    swiftly install 6.0-snapshot
+    swiftly install main-snapshot
     ```
 
 ## Building
@@ -33,13 +33,6 @@ An operating system written in Swift.
 make
 ```
 
-> [!WARNING]
-> If you used swiftly to install Swift, you have to modify `Makefile` until https://github.com/swift-server/swiftly/issues/92 is resolved.
->
-> ```makefile
-> SWIFT := swift-legacy-driver
-> ```
-
 ## Cleaning build outputs
 
 ```shell
diff --git a/Sources/Kernel/kernel.swift b/Sources/Kernel/kernel.swift
index 87ae679..345228f 100644
--- a/Sources/Kernel/kernel.swift
+++ b/Sources/Kernel/kernel.swift
@@ -1,4 +1,4 @@
-@_silgen_name("kmain")
+@_cdecl("kmain")
 public func kmain() {
     initUART()
 
diff --git a/Sources/Kernel/putchar.swift b/Sources/Kernel/putchar.swift
index 5375175..8e56b1b 100644
--- a/Sources/Kernel/putchar.swift
+++ b/Sources/Kernel/putchar.swift
@@ -1,4 +1,4 @@
-@_silgen_name("putchar")
+@_cdecl("putchar")
 @discardableResult
 @inlinable
 public func putchar(_ c: CInt) -> CInt {