diff --git a/lib/compiler/reduce.zig b/lib/compiler/reduce.zig
index 9390bafd61d8..15e545a5aea8 100644
--- a/lib/compiler/reduce.zig
+++ b/lib/compiler/reduce.zig
@@ -68,7 +68,7 @@ pub fn main() !void {
             const arg = args[i];
             if (mem.startsWith(u8, arg, "-")) {
                 if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
-                    const stdout = std.fs.File.stdout().deprecatedWriter();
+                    const stdout = std.fs.File.stdout();
                     try stdout.writeAll(usage);
                     return std.process.cleanExit();
                 } else if (mem.eql(u8, arg, "--")) {
diff --git a/lib/std/Random/benchmark.zig b/lib/std/Random/benchmark.zig
index 3141be3c3c8b..4f6198dee731 100644
--- a/lib/std/Random/benchmark.zig
+++ b/lib/std/Random/benchmark.zig
@@ -122,7 +122,9 @@ fn mode(comptime x: comptime_int) comptime_int {
 }
 
 pub fn main() !void {
-    const stdout = std.fs.File.stdout().deprecatedWriter();
+    var stdout_buffer: [0x100]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
+    const stdout = &stdout_writer.interface;
 
     var buffer: [1024]u8 = undefined;
     var fixed = std.heap.FixedBufferAllocator.init(buffer[0..]);
@@ -139,6 +141,7 @@ pub fn main() !void {
     while (i < args.len) : (i += 1) {
         if (std.mem.eql(u8, args[i], "--mode")) {
             try stdout.print("{}\n", .{builtin.mode});
+            try stdout.flush();
             return;
         } else if (std.mem.eql(u8, args[i], "--filter")) {
             i += 1;
@@ -179,6 +182,8 @@ pub fn main() !void {
             inline for (prngs) |R| {
                 if (filter == null or std.mem.indexOf(u8, R.name, filter.?) != null) {
                     try stdout.print("{s} (long outputs)\n", .{R.name});
+                    try stdout.flush();
+
                     const result_long = try benchmark(R, count, long_block_size);
                     try stdout.print("    {:5} MiB/s\n", .{result_long.throughput / (1 * MiB)});
                 }
@@ -188,6 +193,8 @@ pub fn main() !void {
             inline for (prngs) |R| {
                 if (filter == null or std.mem.indexOf(u8, R.name, filter.?) != null) {
                     try stdout.print("{s} (short outputs)\n", .{R.name});
+                    try stdout.flush();
+
                     const result_short = try benchmark(R, count, short_block_size);
                     try stdout.print("    {:5} MiB/s\n", .{result_short.throughput / (1 * MiB)});
                 }
@@ -199,6 +206,8 @@ pub fn main() !void {
             inline for (csprngs) |R| {
                 if (filter == null or std.mem.indexOf(u8, R.name, filter.?) != null) {
                     try stdout.print("{s} (cryptographic, long outputs)\n", .{R.name});
+                    try stdout.flush();
+
                     const result_long = try benchmark(R, count, long_block_size);
                     try stdout.print("    {:5} MiB/s\n", .{result_long.throughput / (1 * MiB)});
                 }
@@ -208,10 +217,13 @@ pub fn main() !void {
             inline for (csprngs) |R| {
                 if (filter == null or std.mem.indexOf(u8, R.name, filter.?) != null) {
                     try stdout.print("{s} (cryptographic, short outputs)\n", .{R.name});
+                    try stdout.flush();
+
                     const result_short = try benchmark(R, count, short_block_size);
                     try stdout.print("    {:5} MiB/s\n", .{result_short.throughput / (1 * MiB)});
                 }
             }
         }
     }
+    try stdout.flush();
 }
diff --git a/lib/std/crypto/benchmark.zig b/lib/std/crypto/benchmark.zig
index db63404c1165..fb46998f7eaf 100644
--- a/lib/std/crypto/benchmark.zig
+++ b/lib/std/crypto/benchmark.zig
@@ -460,7 +460,8 @@ fn mode(comptime x: comptime_int) comptime_int {
 }
 
 pub fn main() !void {
-    var stdout_buffer: [4096]u8 = undefined;
+    // Size of buffer is about size of printed message.
+    var stdout_buffer: [0x100]u8 = undefined;
     var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
     const stdout = &stdout_writer.interface;
 
diff --git a/lib/std/hash/benchmark.zig b/lib/std/hash/benchmark.zig
index 84d14a35db5e..85a782340aa8 100644
--- a/lib/std/hash/benchmark.zig
+++ b/lib/std/hash/benchmark.zig
@@ -19,8 +19,11 @@ const Hash = struct {
     has_iterative_api: bool = true,
     has_crypto_api: bool = false,
     has_anytype_api: ?[]const comptime_int = null,
+    /// `final` value should be read from this field.
+    has_struct_api: ?[]const u8 = null,
     init_u8s: ?[]const u8 = null,
     init_u64: ?u64 = null,
+    init_default: bool = false,
 };
 
 const hashes = [_]Hash{
@@ -54,6 +57,8 @@ const hashes = [_]Hash{
     Hash{
         .ty = hash.Adler32,
         .name = "adler32",
+        .has_struct_api = "adler",
+        .init_default = true,
     },
     Hash{
         .ty = hash.crc.Crc32,
@@ -112,21 +117,29 @@ pub fn benchmarkHash(comptime H: anytype, bytes: usize, allocator: std.mem.Alloc
 
     const block_count = bytes / block_size;
 
-    var h = blk: {
+    var h: H.ty = blk: {
         if (H.init_u8s) |init| {
-            break :blk H.ty.init(init[0..H.ty.key_length]);
+            break :blk .init(init[0..H.ty.key_length]);
         }
         if (H.init_u64) |init| {
-            break :blk H.ty.init(init);
+            break :blk .init(init);
         }
-        break :blk H.ty.init();
+        if (H.init_default) {
+            break :blk .{};
+        }
+        break :blk .init();
     };
 
     var timer = try Timer.start();
     for (0..block_count) |i| {
         h.update(blocks[i * block_size ..][0..block_size]);
     }
-    const final = if (H.has_crypto_api) @as(u64, @truncate(h.finalInt())) else h.final();
+    const final = if (H.has_struct_api) |field_name|
+        @field(h, field_name)
+    else if (H.has_crypto_api)
+        @as(u64, @truncate(h.finalInt()))
+    else
+        h.final();
     std.mem.doNotOptimizeAway(final);
 
     const elapsed_ns = timer.read();
@@ -340,7 +353,9 @@ fn mode(comptime x: comptime_int) comptime_int {
 }
 
 pub fn main() !void {
-    const stdout = std.fs.File.stdout().deprecatedWriter();
+    var stdout_buffer: [0x100]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
+    const stdout = &stdout_writer.interface;
 
     var buffer: [1024]u8 = undefined;
     var fixed = std.heap.FixedBufferAllocator.init(buffer[0..]);
@@ -360,6 +375,7 @@ pub fn main() !void {
     while (i < args.len) : (i += 1) {
         if (std.mem.eql(u8, args[i], "--mode")) {
             try stdout.print("{}\n", .{builtin.mode});
+            try stdout.flush();
             return;
         } else if (std.mem.eql(u8, args[i], "--seed")) {
             i += 1;
@@ -397,6 +413,7 @@ pub fn main() !void {
             key_size = try std.fmt.parseUnsigned(usize, args[i], 10);
             if (key_size.? > block_size) {
                 try stdout.print("key_size cannot exceed block size of {}\n", .{block_size});
+                try stdout.flush();
                 std.process.exit(1);
             }
         } else if (std.mem.eql(u8, args[i], "--iterative-only")) {
@@ -416,6 +433,7 @@ pub fn main() !void {
 
     if (test_iterative_only and test_small_key_only) {
         try stdout.print("Cannot use iterative-only and small-key-only together!\n", .{});
+        try stdout.flush();
         usage();
         std.process.exit(1);
     }
@@ -428,6 +446,7 @@ pub fn main() !void {
         if (filter == null or std.mem.indexOf(u8, H.name, filter.?) != null) hash: {
             if (!test_iterative_only or H.has_iterative_api) {
                 try stdout.print("{s}\n", .{H.name});
+                try stdout.flush();
 
                 // Always reseed prior to every call so we are hashing the same buffer contents.
                 // This allows easier comparison between different implementations.
@@ -435,6 +454,7 @@ pub fn main() !void {
                     prng.seed(seed);
                     const result = try benchmarkHash(H, count, allocator);
                     try stdout.print("   iterative: {:5} MiB/s [{x:0<16}]\n", .{ result.throughput / (1 * MiB), result.hash });
+                    try stdout.flush();
                 }
 
                 if (!test_iterative_only) {
@@ -447,6 +467,7 @@ pub fn main() !void {
                             result_small.throughput / size,
                             result_small.hash,
                         });
+                        try stdout.flush();
 
                         if (!test_arrays) break :hash;
                         if (H.has_anytype_api) |sizes| {
@@ -464,6 +485,7 @@ pub fn main() !void {
                                         result_ptr.throughput / (1 * MiB),
                                         result_ptr.hash,
                                     });
+                                    try stdout.flush();
                                 }
                             }
                         }
@@ -476,6 +498,7 @@ pub fn main() !void {
                             result_small.throughput / default_small_key_size,
                             result_small.hash,
                         });
+                        try stdout.flush();
 
                         if (!test_arrays) break :hash;
                         if (H.has_anytype_api) |sizes| {
@@ -488,6 +511,7 @@ pub fn main() !void {
                                     result.throughput / (1 * MiB),
                                     result.hash,
                                 });
+                                try stdout.flush();
                             }
                             try stdout.print("   array ptr: \n", .{});
                             inline for (sizes) |exact_size| {
@@ -498,6 +522,7 @@ pub fn main() !void {
                                     result.throughput / (1 * MiB),
                                     result.hash,
                                 });
+                                try stdout.flush();
                             }
                         }
                     }
diff --git a/lib/std/log.zig b/lib/std/log.zig
index ca3896e2da27..113831e4622f 100644
--- a/lib/std/log.zig
+++ b/lib/std/log.zig
@@ -47,8 +47,8 @@
 //!     // Print the message to stderr, silently ignoring any errors
 //!     std.debug.lockStdErr();
 //!     defer std.debug.unlockStdErr();
-//!     const stderr = std.fs.File.stderr().deprecatedWriter();
-//!     nosuspend stderr.print(prefix ++ format ++ "\n", args) catch return;
+//!     var stderr = std.fs.File.stderr().writer(&.{});
+//!     nosuspend stderr.interface.print(prefix ++ format ++ "\n", args) catch return;
 //! }
 //!
 //! pub fn main() void {
diff --git a/lib/std/unicode/throughput_test.zig b/lib/std/unicode/throughput_test.zig
index c13a38b101c9..fd3f46ec584a 100644
--- a/lib/std/unicode/throughput_test.zig
+++ b/lib/std/unicode/throughput_test.zig
@@ -39,35 +39,44 @@ fn benchmarkCodepointCount(buf: []const u8) !ResultCount {
 }
 
 pub fn main() !void {
-    const stdout = std.fs.File.stdout().deprecatedWriter();
+    // Size of buffer is about size of printed message.
+    var stdout_buffer: [0x100]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
+    const stdout = &stdout_writer.interface;
 
     try stdout.print("short ASCII strings\n", .{});
+    try stdout.flush();
     {
         const result = try benchmarkCodepointCount("abc");
         try stdout.print("  count: {:5} MiB/s [{d}]\n", .{ result.throughput / (1 * MiB), result.count });
     }
 
     try stdout.print("short Unicode strings\n", .{});
+    try stdout.flush();
     {
         const result = try benchmarkCodepointCount("ŌŌŌ");
         try stdout.print("  count: {:5} MiB/s [{d}]\n", .{ result.throughput / (1 * MiB), result.count });
     }
 
     try stdout.print("pure ASCII strings\n", .{});
+    try stdout.flush();
     {
         const result = try benchmarkCodepointCount("hello" ** 16);
         try stdout.print("  count: {:5} MiB/s [{d}]\n", .{ result.throughput / (1 * MiB), result.count });
     }
 
     try stdout.print("pure Unicode strings\n", .{});
+    try stdout.flush();
     {
         const result = try benchmarkCodepointCount("こんにちは" ** 16);
         try stdout.print("  count: {:5} MiB/s [{d}]\n", .{ result.throughput / (1 * MiB), result.count });
     }
 
     try stdout.print("mixed ASCII/Unicode strings\n", .{});
+    try stdout.flush();
     {
         const result = try benchmarkCodepointCount("Hyvää huomenta" ** 16);
         try stdout.print("  count: {:5} MiB/s [{d}]\n", .{ result.throughput / (1 * MiB), result.count });
     }
+    try stdout.flush();
 }