diff --git a/lib/std/Io/Threaded.zig b/lib/std/Io/Threaded.zig
index 9f888e1ea9..965266aee9 100644
--- a/lib/std/Io/Threaded.zig
+++ b/lib/std/Io/Threaded.zig
@@ -12787,7 +12787,7 @@ const processSpawn = switch (native_os) {
 fn processSpawnUnsupported(userdata: ?*anyopaque, options: process.SpawnOptions) process.SpawnError!process.Child {
     _ = userdata;
     _ = options;
-    return error.OperationUnsupported;
+    return error.Unexpected;
 }
 
 fn processSpawnPosix(userdata: ?*anyopaque, options: process.SpawnOptions) process.SpawnError!process.Child {
@@ -12995,6 +12995,7 @@ fn processSpawnPosix(userdata: ?*anyopaque, options: process.SpawnOptions) proce
 }
 
 fn childWait(userdata: ?*anyopaque, child: *std.process.Child) process.Child.WaitError!process.Child.Term {
+    if (native_os == .wasi) unreachable;
     const t: *Threaded = @ptrCast(@alignCast(userdata));
     switch (native_os) {
         .windows => return childWaitWindows(t, child),
@@ -13003,6 +13004,7 @@ fn childWait(userdata: ?*anyopaque, child: *std.process.Child) process.Child.Wai
 }
 
 fn childKill(userdata: ?*anyopaque, child: *std.process.Child) void {
+    if (native_os == .wasi) unreachable;
     const t: *Threaded = @ptrCast(@alignCast(userdata));
     if (is_windows) {
         childKillWindows(t, child, 1) catch childCleanupWindows(child);
diff --git a/lib/std/posix/test.zig b/lib/std/posix/test.zig
index d95789c254..6b56f01709 100644
--- a/lib/std/posix/test.zig
+++ b/lib/std/posix/test.zig
@@ -22,10 +22,10 @@ const tmpDir = std.testing.tmpDir;
 
 test "check WASI CWD" {
     if (native_os == .wasi) {
-        if (std.options.wasiCwd() != 3) {
+        const cwd: Dir = .cwd();
+        if (cwd.handle != 3) {
             @panic("WASI code that uses cwd (like this test) needs a preopen for cwd (add '--dir=.' to wasmtime)");
         }
-
         if (!builtin.link_libc) {
             // WASI without-libc hardcodes fd 3 as the FDCWD token so it can be passed directly to WASI calls
             try expectEqual(3, posix.AT.FDCWD);
diff --git a/lib/std/process/Args.zig b/lib/std/process/Args.zig
index e5c106c8f4..7ecd1d2f9b 100644
--- a/lib/std/process/Args.zig
+++ b/lib/std/process/Args.zig
@@ -10,8 +10,14 @@ const testing = std.testing;
 
 vector: Vector,
 
+/// On WASI without libc, this is `void` because the environment has to be
+/// queried and heap-allocated at runtime.
 pub const Vector = switch (native_os) {
     .windows => []const u16, // WTF-16 encoded
+    .wasi => switch (builtin.link_libc) {
+        false => void,
+        true => []const [*:0]const u8,
+    },
     .freestanding, .other => void,
     else => []const [*:0]const u8,
 };
@@ -457,6 +463,8 @@ pub fn iterateAllocator(a: Args, gpa: Allocator) Iterator.InitError!Iterator {
     return .initAllocator(a, gpa);
 }
 
+pub const ToSliceError = Iterator.Windows.InitError || Iterator.Wasi.InitError;
+
 /// Returned value may reference several allocations; call `freeSlice` to
 /// release.
 ///
@@ -464,19 +472,19 @@ pub fn iterateAllocator(a: Args, gpa: Allocator) Iterator.InitError!Iterator {
 ///   [WTF-8](https://wtf-8.codeberg.page/).
 /// * On other platforms, the result is an opaque sequence of bytes with no
 ///   particular encoding.
-pub fn toSlice(a: Args, gpa: Allocator) Allocator.Error![][:0]u8 {
+pub fn toSlice(a: Args, gpa: Allocator) ToSliceError![][:0]u8 {
     var it = try a.iterateAllocator(gpa);
     defer it.deinit();
 
-    var contents = std.array_list.Managed(u8).init(gpa);
-    defer contents.deinit();
+    var contents: std.ArrayList(u8) = .empty;
+    defer contents.deinit(gpa);
 
-    var slice_list = std.array_list.Managed(usize).init(gpa);
-    defer slice_list.deinit();
+    var slice_list: std.ArrayList(usize) = .empty;
+    defer slice_list.deinit(gpa);
 
     while (it.next()) |arg| {
-        try contents.appendSlice(arg[0 .. arg.len + 1]);
-        try slice_list.append(arg.len);
+        try contents.appendSlice(gpa, arg[0 .. arg.len + 1]);
+        try slice_list.append(gpa, arg.len);
     }
 
     const contents_slice = contents.items;
diff --git a/lib/std/process/Environ.zig b/lib/std/process/Environ.zig
index 8254cf093a..39ca80ca8b 100644
--- a/lib/std/process/Environ.zig
+++ b/lib/std/process/Environ.zig
@@ -757,6 +757,9 @@ test Map {
 }
 
 test "convert from Environ to Map and back again" {
+    if (native_os == .windows) return;
+    if (native_os == .wasi and !builtin.link_libc) return;
+
     const gpa = testing.allocator;
 
     var map: Map = .init(gpa);
@@ -769,11 +772,7 @@ test "convert from Environ to Map and back again" {
     defer arena_allocator.deinit();
     const arena = arena_allocator.allocator();
 
-    const environ: Environ = switch (native_os) {
-        .windows => return error.SkipZigTest,
-        .wasi => if (!builtin.libc) return error.SkipZigTest,
-        else => .{ .block = try map.createBlockPosix(arena, .{}) },
-    };
+    const environ: Environ = .{ .block = try map.createBlockPosix(arena, .{}) };
 
     try testing.expectEqual(true, environ.contains(gpa, "FOO"));
     try testing.expectEqual(false, environ.contains(gpa, "BAR"));
diff --git a/lib/std/start.zig b/lib/std/start.zig
index e6b95cb51d..8a33053634 100644
--- a/lib/std/start.zig
+++ b/lib/std/start.zig
@@ -55,7 +55,7 @@ comptime {
             if (!@hasDecl(root, wasm_start_sym) and @hasDecl(root, "main")) {
                 // Only call main when defined. For WebAssembly it's allowed to pass `-fno-entry` in which
                 // case it's not required to provide an entrypoint such as main.
-                @export(&wasi_start, .{ .name = wasm_start_sym });
+                @export(&startWasi, .{ .name = wasm_start_sym });
             }
         } else if (native_arch.isWasm() and native_os == .freestanding) {
             // Only call main when defined. For WebAssembly it's allowed to pass `-fno-entry` in which
@@ -90,7 +90,7 @@ fn wasm_freestanding_start() callconv(.c) void {
     _ = @call(.always_inline, callMain, .{ {}, {} });
 }
 
-fn wasi_start() callconv(.c) void {
+fn startWasi() callconv(.c) void {
     // The function call is marked inline because for some reason LLVM in
     // release mode fails to inline it, and we want fewer call frames in stack traces.
     switch (builtin.wasi_exec_model) {