diff --git a/ci/launcher b/ci/launcher
index 011f83b..3a4f31f 100755
--- a/ci/launcher
+++ b/ci/launcher
@@ -3,6 +3,16 @@ set -xeuo pipefail
 
 ZIG=${ZIG:-bazel run "$@" @zig_sdk//:zig --}
 
+for target in \
+    aarch64-linux-gnu.2.19 \
+    aarch64-macos-none \
+    x86_64-linux-gnu.2.19 \
+    x86_64-macos-none \
+    x86_64-windows-gnu
+do
+    $ZIG build-exe -fno-emit-bin -target $target toolchain/launcher.zig
+done
+
 # until bazel-zig-cc gets a zig toolchain, run launcher's unit tests here.
 $ZIG test toolchain/launcher.zig
 
diff --git a/toolchain/launcher.zig b/toolchain/launcher.zig
index 1043f49..b2a907a 100644
--- a/toolchain/launcher.zig
+++ b/toolchain/launcher.zig
@@ -121,7 +121,7 @@ pub fn main() u8 {
 
     switch (action) {
         .early_ok => return 0,
-        .early_err => |msg| return fatal(msg),
+        .early_err => |msg| return fatal("{s}", .{msg}),
         .exec => |params| {
             if (builtin.os.tag == .windows)
                 return spawnWindows(arena, params)
@@ -240,7 +240,7 @@ fn parseFatal(
 }
 
 pub fn fatal(comptime fmt: []const u8, args: anytype) u8 {
-    fmt.debug.print(fmt, args);
+    std.debug.print(fmt, args);
     return 1;
 }