diff --git a/lib/std/io.zig b/lib/std/io.zig
index 64560c6fe3bf..df220e24898a 100644
--- a/lib/std/io.zig
+++ b/lib/std/io.zig
@@ -375,9 +375,6 @@ pub const BufferedReader = @import("io/buffered_reader.zig").BufferedReader;
 pub const bufferedReader = @import("io/buffered_reader.zig").bufferedReader;
 pub const bufferedReaderSize = @import("io/buffered_reader.zig").bufferedReaderSize;
 
-pub const PeekStream = @import("io/peek_stream.zig").PeekStream;
-pub const peekStream = @import("io/peek_stream.zig").peekStream;
-
 pub const FixedBufferStream = @import("io/fixed_buffer_stream.zig").FixedBufferStream;
 pub const fixedBufferStream = @import("io/fixed_buffer_stream.zig").fixedBufferStream;
 
@@ -707,7 +704,6 @@ test {
     _ = @import("io/counting_writer.zig");
     _ = @import("io/counting_reader.zig");
     _ = @import("io/fixed_buffer_stream.zig");
-    _ = @import("io/peek_stream.zig");
     _ = @import("io/seekable_stream.zig");
     _ = @import("io/stream_source.zig");
     _ = @import("io/test.zig");
diff --git a/lib/std/io/peek_stream.zig b/lib/std/io/peek_stream.zig
deleted file mode 100644
index 9c28a80cef9d..000000000000
--- a/lib/std/io/peek_stream.zig
+++ /dev/null
@@ -1,116 +0,0 @@
-const std = @import("../std.zig");
-const assert = std.debug.assert;
-const io = std.io;
-const mem = std.mem;
-const testing = std.testing;
-
-/// Creates a stream which supports 'un-reading' data, so that it can be read again.
-/// This makes look-ahead style parsing much easier.
-/// TODO merge this with `std.io.BufferedReader`: https://github.com/ziglang/zig/issues/4501
-pub fn PeekStream(
-    comptime buffer_type: std.fifo.LinearFifoBufferType,
-    comptime ReaderType: type,
-) type {
-    return struct {
-        unbuffered_reader: ReaderType,
-        fifo: FifoType,
-
-        pub const Error = ReaderType.Error;
-        pub const Reader = io.Reader(*Self, Error, read);
-
-        const Self = @This();
-        const FifoType = std.fifo.LinearFifo(u8, buffer_type);
-
-        pub const init = switch (buffer_type) {
-            .Static => initStatic,
-            .Slice => initSlice,
-            .Dynamic => initDynamic,
-        };
-
-        fn initStatic(base: ReaderType) Self {
-            comptime assert(buffer_type == .Static);
-            return .{
-                .unbuffered_reader = base,
-                .fifo = FifoType.init(),
-            };
-        }
-
-        fn initSlice(base: ReaderType, buf: []u8) Self {
-            comptime assert(buffer_type == .Slice);
-            return .{
-                .unbuffered_reader = base,
-                .fifo = FifoType.init(buf),
-            };
-        }
-
-        fn initDynamic(base: ReaderType, allocator: mem.Allocator) Self {
-            comptime assert(buffer_type == .Dynamic);
-            return .{
-                .unbuffered_reader = base,
-                .fifo = FifoType.init(allocator),
-            };
-        }
-
-        pub fn putBackByte(self: *Self, byte: u8) !void {
-            try self.putBack(&[_]u8{byte});
-        }
-
-        pub fn putBack(self: *Self, bytes: []const u8) !void {
-            try self.fifo.unget(bytes);
-        }
-
-        pub fn read(self: *Self, dest: []u8) Error!usize {
-            // copy over anything putBack()'d
-            var dest_index = self.fifo.read(dest);
-            if (dest_index == dest.len) return dest_index;
-
-            // ask the backing stream for more
-            dest_index += try self.unbuffered_reader.read(dest[dest_index..]);
-            return dest_index;
-        }
-
-        pub fn reader(self: *Self) Reader {
-            return .{ .context = self };
-        }
-    };
-}
-
-pub fn peekStream(
-    comptime lookahead: comptime_int,
-    underlying_stream: anytype,
-) PeekStream(.{ .Static = lookahead }, @TypeOf(underlying_stream)) {
-    return PeekStream(.{ .Static = lookahead }, @TypeOf(underlying_stream)).init(underlying_stream);
-}
-
-test "PeekStream" {
-    const bytes = [_]u8{ 1, 2, 3, 4, 5, 6, 7, 8 };
-    var fbs = io.fixedBufferStream(&bytes);
-    var ps = peekStream(2, fbs.reader());
-
-    var dest: [4]u8 = undefined;
-
-    try ps.putBackByte(9);
-    try ps.putBackByte(10);
-
-    var read = try ps.reader().read(dest[0..4]);
-    try testing.expect(read == 4);
-    try testing.expect(dest[0] == 10);
-    try testing.expect(dest[1] == 9);
-    try testing.expect(mem.eql(u8, dest[2..4], bytes[0..2]));
-
-    read = try ps.reader().read(dest[0..4]);
-    try testing.expect(read == 4);
-    try testing.expect(mem.eql(u8, dest[0..4], bytes[2..6]));
-
-    read = try ps.reader().read(dest[0..4]);
-    try testing.expect(read == 2);
-    try testing.expect(mem.eql(u8, dest[0..2], bytes[6..8]));
-
-    try ps.putBackByte(11);
-    try ps.putBackByte(12);
-
-    read = try ps.reader().read(dest[0..4]);
-    try testing.expect(read == 2);
-    try testing.expect(dest[0] == 12);
-    try testing.expect(dest[1] == 11);
-}