diff --git a/src/output/plugins/PipeWireOutputPlugin.cxx b/src/output/plugins/PipeWireOutputPlugin.cxx
index 18821b105..6cb267b09 100644
--- a/src/output/plugins/PipeWireOutputPlugin.cxx
+++ b/src/output/plugins/PipeWireOutputPlugin.cxx
@@ -29,7 +29,6 @@
 #include "util/Domain.hxx"
 #include "util/ScopeExit.hxx"
 #include "util/StringCompare.hxx"
-#include "util/WritableBuffer.hxx"
 #include "Log.hxx"
 #include "tag/Format.hxx"
 #include "config.h" // for ENABLE_DSD
diff --git a/src/tag/FixString.cxx b/src/tag/FixString.cxx
index d1877cfaa..90c79652c 100644
--- a/src/tag/FixString.cxx
+++ b/src/tag/FixString.cxx
@@ -20,7 +20,6 @@
 #include "FixString.hxx"
 #include "util/AllocatedArray.hxx"
 #include "util/CharUtil.hxx"
-#include "util/WritableBuffer.hxx"
 #include "util/StringView.hxx"
 #include "util/UTF8.hxx"
 
diff --git a/src/util/WritableBuffer.hxx b/src/util/WritableBuffer.hxx
deleted file mode 100644
index f93125a12..000000000
--- a/src/util/WritableBuffer.hxx
+++ /dev/null
@@ -1,311 +0,0 @@
-/*
- * Copyright 2013-2022 Max Kellermann <max.kellermann@gmail.com>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the
- * distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
- * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#pragma once
-
-#include "ConstBuffer.hxx"
-
-#include <cassert>
-#include <cstddef>
-
-#if __cplusplus >= 202002 || (defined(__GNUC__) && __GNUC__ >= 10)
-#include <version>
-#endif
-
-#ifdef __cpp_lib_span
-#include <span>
-#endif
-
-template<typename T>
-struct WritableBuffer;
-
-template<>
-struct WritableBuffer<void> {
-	typedef std::size_t size_type;
-	using value_type = void;
-	using pointer = void *;
-	using const_pointer = const void *;
-	using iterator = pointer;
-	using const_iterator = const_pointer;
-
-	pointer data;
-	size_type size;
-
-	WritableBuffer() = default;
-
-	constexpr WritableBuffer(std::nullptr_t) noexcept
-		:data(nullptr), size(0) {}
-
-	constexpr WritableBuffer(pointer _data, size_type _size) noexcept
-		:data(_data), size(_size) {}
-
-#ifdef __cpp_lib_span
-	constexpr WritableBuffer(std::span<std::byte> s) noexcept
-		:data(s.data()), size(s.size()) {}
-#endif
-
-	constexpr static WritableBuffer<void> FromVoid(WritableBuffer<void> other) noexcept {
-		return other;
-	}
-
-	constexpr WritableBuffer<void> ToVoid() const noexcept {
-		return *this;
-	}
-
-	constexpr operator ConstBuffer<void>() const noexcept {
-		return {data, size};
-	}
-
-	constexpr bool IsNull() const noexcept {
-		return data == nullptr;
-	}
-
-	constexpr bool operator==(std::nullptr_t) const noexcept {
-		return data == nullptr;
-	}
-
-	constexpr bool operator!=(std::nullptr_t) const noexcept {
-		return data != nullptr;
-	}
-
-	constexpr bool empty() const noexcept {
-		return size == 0;
-	}
-
-#ifdef __cpp_lib_span
-	constexpr operator std::span<std::byte>() const noexcept {
-		return {static_cast<std::byte *>(data), size};
-	}
-
-	constexpr operator std::span<const std::byte>() const noexcept {
-		return {static_cast<const std::byte *>(data), size};
-	}
-#endif
-};
-
-/**
- * A reference to a memory area that is writable.
- *
- * @see ConstBuffer
- */
-template<typename T>
-struct WritableBuffer {
-	using size_type = std::size_t;
-	using value_type = T;
-	using reference = T &;
-	using const_reference = const T &;
-	using pointer = T *;
-	using const_pointer = const T *;
-	using iterator = pointer;
-	using const_iterator = const_pointer;
-
-	pointer data;
-	size_type size;
-
-	WritableBuffer() = default;
-
-	constexpr WritableBuffer(std::nullptr_t) noexcept
-		:data(nullptr), size(0) {}
-
-	constexpr WritableBuffer(pointer _data, size_type _size) noexcept
-		:data(_data), size(_size) {}
-
-	constexpr WritableBuffer(pointer _data, pointer _end) noexcept
-		:data(_data), size(_end - _data) {}
-
-#ifdef __cpp_lib_span
-	constexpr WritableBuffer(std::span<T> s) noexcept
-		:data(s.data()), size(s.size()) {}
-#endif
-
-	/**
-	 * Convert array to WritableBuffer instance.
-	 */
-	template<size_type _size>
-	constexpr WritableBuffer(T (&_data)[_size]) noexcept
-		:data(_data), size(_size) {}
-
-	constexpr operator ConstBuffer<T>() const noexcept {
-		return {data, size};
-	}
-
-	/**
-	 * Cast a WritableBuffer<void> to a WritableBuffer<T>,
-	 * rounding down to the next multiple of T's size.
-	 */
-	static constexpr WritableBuffer<T> FromVoidFloor(WritableBuffer<void> other) noexcept {
-		static_assert(sizeof(T) > 0, "Empty base type");
-		return WritableBuffer<T>(pointer(other.data),
-					 other.size / sizeof(T));
-	}
-
-	/**
-	 * Cast a WritableBuffer<void> to a WritableBuffer<T>.  A "void"
-	 * buffer records its size in bytes, and when casting to "T",
-	 * the assertion below ensures that the size is a multiple of
-	 * sizeof(T).
-	 */
-	static constexpr WritableBuffer<T> FromVoid(WritableBuffer<void> other) noexcept {
-		static_assert(sizeof(T) > 0, "Empty base type");
-		assert(other.size % sizeof(T) == 0);
-		return FromVoidFloor(other);
-	}
-
-	constexpr WritableBuffer<void> ToVoid() const noexcept {
-		static_assert(sizeof(T) > 0, "Empty base type");
-		return WritableBuffer<void>(data, size * sizeof(T));
-	}
-
-	constexpr bool IsNull() const noexcept {
-		return data == nullptr;
-	}
-
-	constexpr bool operator==(std::nullptr_t) const noexcept {
-		return data == nullptr;
-	}
-
-	constexpr bool operator!=(std::nullptr_t) const noexcept {
-		return data != nullptr;
-	}
-
-	constexpr bool empty() const noexcept {
-		return size == 0;
-	}
-
-	constexpr iterator begin() const noexcept {
-		return data;
-	}
-
-	constexpr iterator end() const noexcept {
-		return data + size;
-	}
-
-	constexpr const_iterator cbegin() const noexcept {
-		return data;
-	}
-
-	constexpr const_iterator cend() const noexcept {
-		return data + size;
-	}
-
-	constexpr reference operator[](size_type i) const noexcept {
-		assert(i < size);
-
-		return data[i];
-	}
-
-	/**
-	 * Returns a reference to the first element.  Buffer must not
-	 * be empty.
-	 */
-	constexpr reference front() const noexcept {
-		assert(!empty());
-		return data[0];
-	}
-
-	/**
-	 * Returns a reference to the last element.  Buffer must not
-	 * be empty.
-	 */
-	constexpr reference back() const noexcept {
-		assert(!empty());
-		return data[size - 1];
-	}
-
-	/**
-	 * Remove the first element (by moving the head pointer, does
-	 * not actually modify the buffer).  Buffer must not be empty.
-	 */
-	constexpr void pop_front() noexcept {
-		assert(!empty());
-
-		++data;
-		--size;
-	}
-
-	/**
-	 * Remove the last element (by moving the tail pointer, does
-	 * not actually modify the buffer).  Buffer must not be empty.
-	 */
-	constexpr void pop_back() noexcept {
-		assert(!empty());
-
-		--size;
-	}
-
-	/**
-	 * Remove the first element and return a reference to it.
-	 * Buffer must not be empty.
-	 */
-	constexpr reference shift() noexcept {
-		reference result = front();
-		pop_front();
-		return result;
-	}
-
-	constexpr void skip_front(size_type n) noexcept {
-		assert(size >= n);
-
-		data += n;
-		size -= n;
-	}
-
-	/**
-	 * Move the front pointer to the given address, and adjust the
-	 * size attribute to retain the old end address.
-	 */
-	void MoveFront(pointer new_data) noexcept {
-		assert(IsNull() == (new_data == nullptr));
-		assert(new_data <= end());
-
-		size = end() - new_data;
-		data = new_data;
-	}
-
-	/**
-	 * Move the end pointer to the given address (by adjusting the
-	 * size).
-	 */
-	void SetEnd(pointer new_end) noexcept {
-		assert(IsNull() == (new_end == nullptr));
-		assert(new_end >= begin());
-
-		size = new_end - data;
-	}
-
-#ifdef __cpp_lib_span
-	constexpr operator std::span<T>() const noexcept {
-		return {data, size};
-	}
-
-	constexpr operator std::span<const T>() const noexcept {
-		return {data, size};
-	}
-#endif
-};