diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index e679702..578e72d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -45,8 +45,8 @@ jobs:
     - name: Install (Ubuntu)
       if: matrix.os == 'ubuntu'
       run: |
-        curl -L https://ziglang.org/download/0.8.0/zig-linux-x86_64-0.8.0.tar.xz | tar -xJf -
-        echo "$(pwd)/zig-linux-x86_64-0.8.0" >> $GITHUB_PATH
+        curl -L https://ziglang.org/download/0.9.0/zig-linux-x86_64-0.9.0.tar.xz | tar -xJf -
+        echo "$(pwd)/zig-linux-x86_64-0.9.0" >> $GITHUB_PATH
 
     - name: Install (Mac OS)
       if: matrix.os == 'macos'
@@ -55,7 +55,7 @@ jobs:
     - name: Install (Windows)
       if: matrix.os == 'windows'
       run: |
-        choco install zig --version 0.8.0
+        choco install zig --version 0.9.0
         ln -s $(which python) /usr/bin/python3
 
     - run: python ./get-toolchain.py
diff --git a/riscv-zig-blink/README.md b/riscv-zig-blink/README.md
index 7b4c5e9..39c330c 100644
--- a/riscv-zig-blink/README.md
+++ b/riscv-zig-blink/README.md
@@ -1,12 +1,12 @@
 # riscv-zig-blink
 
-Written against zig 0.8.0
+Written against zig 0.9.0
 
 You can obtain the zig compiler via https://ziglang.org/download/
 e.g. a linux user might run:
 ```
-curl -L https://ziglang.org/download/0.8.0/zig-linux-x86_64-0.8.0.tar.xz | tar -xJf -
-alias zig=./zig-linux-x86_64-0.8.0/zig
+curl -L https://ziglang.org/download/0.9.0/zig-linux-x86_64-0.9.0.tar.xz | tar -xJf -
+alias zig=./zig-linux-x86_64-0.9.0/zig
 ```
 
 Run `zig build --help` from this directory for usage and options.
diff --git a/riscv-zig-blink/build.zig b/riscv-zig-blink/build.zig
index 4513a5e..d28629f 100644
--- a/riscv-zig-blink/build.zig
+++ b/riscv-zig-blink/build.zig
@@ -14,7 +14,7 @@ pub fn build(b: *Builder) void {
             .explicit = &std.Target.riscv.cpu.generic_rv32,
         },
     });
-    elf.setLinkerScriptPath("ld/linker.ld");
+    elf.setLinkerScriptPath(.{ .path = "ld/linker.ld" });
     elf.setBuildMode(mode);
     // The ELF file contains debug symbols and can be passed to gdb for remote debugging
     if (b.option(bool, "emit-elf", "Should an ELF file be emitted in the current directory?") orelse false) {
diff --git a/riscv-zig-blink/src/fomu.zig b/riscv-zig-blink/src/fomu.zig
index 239f714..6ff5bf5 100644
--- a/riscv-zig-blink/src/fomu.zig
+++ b/riscv-zig-blink/src/fomu.zig
@@ -17,6 +17,7 @@ comptime {
 /// Panic function that sets LED to red and flashing + prints the panic message over messible
 pub fn panic(message: []const u8, stack_trace: ?*std.builtin.StackTrace) noreturn {
     @setCold(true);
+    _ = stack_trace;
 
     // Put LED into non-raw flashing mode
     RGB.CTRL.* = .{
@@ -49,6 +50,7 @@ pub fn panic(message: []const u8, stack_trace: ?*std.builtin.StackTrace) noretur
 
 const WriteError = error{};
 fn messibleWrite(self: void, bytes: []const u8) WriteError!usize {
+    _ = self;
     while (true) {
         const bytes_written = MESSIBLE.write(bytes);
         if (bytes_written != 0) return bytes_written;
@@ -58,6 +60,7 @@ pub const messibleWriter = std.io.Writer(void, WriteError, messibleWrite){ .cont
 
 const ReadError = error{};
 fn messibleRead(self: void, buffer: []u8) ReadError!usize {
+    _ = self;
     while (true) {
         const bytes_read = MESSIBLE.read(buffer);
         if (bytes_read != 0) return bytes_read;
diff --git a/riscv-zig-blink/src/fomu/rgb.zig b/riscv-zig-blink/src/fomu/rgb.zig
index edcab01..1d0c606 100644
--- a/riscv-zig-blink/src/fomu/rgb.zig
+++ b/riscv-zig-blink/src/fomu/rgb.zig
@@ -14,7 +14,7 @@ pub const RGB = struct {
     /// Writing to this register has no immediate effect – data isn’t written until the DAT register is written.
     pub const ADDR = @intToPtr(*volatile u4, base + 0x4);
 
-    pub const Register = enum {
+    pub const Register = enum(u4) {
         PWRR = 1,
         PWRG = 2,
         PWRB = 3,