diff --git a/libaegisub/common/cajun/writer.cpp b/libaegisub/common/cajun/writer.cpp
index 61a12163e..b2724f64b 100644
--- a/libaegisub/common/cajun/writer.cpp
+++ b/libaegisub/common/cajun/writer.cpp
@@ -9,7 +9,6 @@ Author: Terry Caton
 #include "libaegisub/cajun/writer.h"
 
 #include <cmath>
-#include <iostream>
 #include <iomanip>
 
 /*
diff --git a/libaegisub/common/hotkey.cpp b/libaegisub/common/hotkey.cpp
index d1c208b83..e8a124380 100644
--- a/libaegisub/common/hotkey.cpp
+++ b/libaegisub/common/hotkey.cpp
@@ -30,7 +30,6 @@
 #include <boost/algorithm/string/join.hpp>
 #include <boost/range/adaptor/map.hpp>
 #include <cmath>
-#include <fstream>
 #include <tuple>
 
 namespace agi {
diff --git a/libaegisub/common/io.cpp b/libaegisub/common/io.cpp
index e4c54ba52..aa7217aa5 100644
--- a/libaegisub/common/io.cpp
+++ b/libaegisub/common/io.cpp
@@ -30,17 +30,16 @@
 namespace agi {
 	namespace io {
 
-std::unique_ptr<std::ifstream> Open(fs::path const& file, bool binary) {
+std::unique_ptr<std::istream> Open(fs::path const& file, bool binary) {
 	LOG_D("agi/io/open/file") << file;
 	acs::CheckFileRead(file);
 
-	std::unique_ptr<std::ifstream> stream(
-		new boost::filesystem::ifstream(file, (binary ? std::ios::binary : std::ios::in)));
+	auto stream = util::make_unique<boost::filesystem::ifstream>(file, (binary ? std::ios::binary : std::ios::in));
 
 	if (stream->fail())
 		throw IOFatal("Unknown fatal error as occurred");
 
-	return stream;
+	return std::unique_ptr<std::istream>(stream.release());
 }
 
 Save::Save(fs::path const& file, bool binary)
@@ -63,7 +62,7 @@ Save::Save(fs::path const& file, bool binary)
 }
 
 Save::~Save() {
-	fp->close(); // Need to close before rename on Windows to unlock the file
+	fp.reset(); // Need to close before rename on Windows to unlock the file
 	for (int i = 0; i < 10; ++i) {
 		try {
 			fs::Rename(tmp_name, file_name);
diff --git a/libaegisub/common/keyframe.cpp b/libaegisub/common/keyframe.cpp
index 5811a0b0b..b4efe06bf 100644
--- a/libaegisub/common/keyframe.cpp
+++ b/libaegisub/common/keyframe.cpp
@@ -22,7 +22,6 @@
 #include "libaegisub/keyframe.h"
 
 #include <algorithm>
-#include <fstream>
 
 #include "libaegisub/io.h"
 #include "libaegisub/line_iterator.h"
@@ -78,14 +77,14 @@ char x264(std::string const& line) {
 namespace agi { namespace keyframe {
 void Save(agi::fs::path const& filename, std::vector<int> const& keyframes) {
 	io::Save file(filename);
-	std::ofstream& of = file.Get();
+	std::ostream& of = file.Get();
 	of << "# keyframe format v1" << std::endl;
 	of << "fps " << 0 << std::endl;
 	boost::copy(keyframes, std::ostream_iterator<int>(of, "\n"));
 }
 
 std::vector<int> Load(agi::fs::path const& filename) {
-	std::unique_ptr<std::ifstream> file(io::Open(filename));
+	auto file = io::Open(filename);
 	std::istream &is(*file);
 
 	std::string header;
diff --git a/libaegisub/common/mru.cpp b/libaegisub/common/mru.cpp
index 0c65638e3..03bf165f6 100644
--- a/libaegisub/common/mru.cpp
+++ b/libaegisub/common/mru.cpp
@@ -28,8 +28,6 @@
 #include "libaegisub/option.h"
 #include "libaegisub/option_value.h"
 
-#include <fstream>
-
 namespace agi {
 
 MRUManager::MRUManager(agi::fs::path const& config, std::pair<const char *, size_t> default_config, agi::Options *options)
diff --git a/libaegisub/common/option.cpp b/libaegisub/common/option.cpp
index 0d75c0395..749ec5a0b 100644
--- a/libaegisub/common/option.cpp
+++ b/libaegisub/common/option.cpp
@@ -34,7 +34,6 @@
 #include <boost/interprocess/streams/bufferstream.hpp>
 #include <boost/range/adaptor/map.hpp>
 #include <cassert>
-#include <fstream>
 #include <memory>
 
 namespace {
diff --git a/libaegisub/common/thesaurus.cpp b/libaegisub/common/thesaurus.cpp
index ed1d35255..a1bb801e0 100644
--- a/libaegisub/common/thesaurus.cpp
+++ b/libaegisub/common/thesaurus.cpp
@@ -28,8 +28,6 @@
 #include <boost/phoenix/operator/comparison.hpp>
 #include <boost/phoenix/core/argument.hpp>
 
-#include <fstream>
-
 using boost::phoenix::placeholders::_1;
 
 namespace agi {
diff --git a/libaegisub/common/vfr.cpp b/libaegisub/common/vfr.cpp
index 4ee0be669..355095841 100644
--- a/libaegisub/common/vfr.cpp
+++ b/libaegisub/common/vfr.cpp
@@ -29,7 +29,6 @@
 #include <boost/interprocess/streams/bufferstream.hpp>
 #include <boost/range/algorithm.hpp>
 #include <cmath>
-#include <fstream>
 #include <functional>
 #include <iterator>
 #include <list>
diff --git a/libaegisub/include/libaegisub/cajun/reader.h b/libaegisub/include/libaegisub/cajun/reader.h
index 16e18b8ba..6d889be38 100644
--- a/libaegisub/include/libaegisub/cajun/reader.h
+++ b/libaegisub/include/libaegisub/cajun/reader.h
@@ -10,7 +10,6 @@ Author: Terry Caton
 
 #include "elements.h"
 
-#include <iostream>
 #include <vector>
 
 namespace json
diff --git a/libaegisub/include/libaegisub/io.h b/libaegisub/include/libaegisub/io.h
index 4ba52eaf5..4142aa4db 100644
--- a/libaegisub/include/libaegisub/io.h
+++ b/libaegisub/include/libaegisub/io.h
@@ -29,17 +29,17 @@ namespace agi {
 DEFINE_BASE_EXCEPTION_NOINNER(IOError, Exception)
 DEFINE_SIMPLE_EXCEPTION_NOINNER(IOFatal, IOError, "io/fatal")
 
-std::unique_ptr<std::ifstream> Open(fs::path const& file, bool binary = false);
+std::unique_ptr<std::istream> Open(fs::path const& file, bool binary = false);
 
 class Save {
-	std::unique_ptr<std::ofstream> fp;
+	std::unique_ptr<std::ostream> fp;
 	const fs::path file_name;
 	const fs::path tmp_name;
 
 public:
 	Save(fs::path const& file, bool binary = false);
 	~Save();
-	std::ofstream& Get() { return *fp; }
+	std::ostream& Get() { return *fp; }
 };
 
 	} // namespace io
diff --git a/libaegisub/lagi_pre.h b/libaegisub/lagi_pre.h
index a206b3b8d..2bffbbfbc 100644
--- a/libaegisub/lagi_pre.h
+++ b/libaegisub/lagi_pre.h
@@ -37,10 +37,8 @@
 
 #include <algorithm>
 #include <deque>
-#include <fstream>
 #include <functional>
 #include <iomanip>
-#include <iostream>
 #include <iterator>
 #include <list>
 #include <locale>
diff --git a/src/ass_attachment.cpp b/src/ass_attachment.cpp
index f5fba865b..044df14ef 100644
--- a/src/ass_attachment.cpp
+++ b/src/ass_attachment.cpp
@@ -24,7 +24,6 @@
 
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/range/iterator_range.hpp>
-#include <fstream>
 
 AssAttachment::AssAttachment(AssAttachment const& rgt)
 : entry_data(rgt.entry_data)
diff --git a/src/ass_style_storage.cpp b/src/ass_style_storage.cpp
index 2d6aea5c8..45a2dba8b 100644
--- a/src/ass_style_storage.cpp
+++ b/src/ass_style_storage.cpp
@@ -44,7 +44,6 @@
 #include <libaegisub/util.h>
 
 #include <boost/algorithm/string/predicate.hpp>
-#include <fstream>
 
 AssStyleStorage::~AssStyleStorage() { }
 void AssStyleStorage::clear() { style.clear(); }
@@ -67,7 +66,7 @@ void AssStyleStorage::Load(agi::fs::path const& filename) {
 	clear();
 
 	try {
-		std::unique_ptr<std::ifstream> in(agi::io::Open(file));
+		auto in = agi::io::Open(file);
 		for (auto const& line : agi::line_iterator<std::string>(*in)) {
 			try {
 				style.emplace_back(agi::util::make_unique<AssStyle>(line));
diff --git a/src/audio_controller.cpp b/src/audio_controller.cpp
index b56b1f9c7..5d35a6bca 100644
--- a/src/audio_controller.cpp
+++ b/src/audio_controller.cpp
@@ -54,7 +54,6 @@
 #include <libaegisub/path.h>
 
 #include <algorithm>
-#include <fstream>
 
 AudioController::AudioController(agi::Context *context)
 : context(context)
@@ -373,7 +372,7 @@ void AudioController::SaveClip(agi::fs::path const& filename, TimeRange const& r
 	if (filename.empty() || start_sample > provider->GetNumSamples() || range.length() == 0) return;
 
 	agi::io::Save outfile(filename, true);
-	std::ofstream& out(outfile.Get());
+	std::ostream& out(outfile.Get());
 
 	size_t bytes_per_sample = provider->GetBytesPerSample() * provider->GetChannels();
 	size_t bufsize = (end_sample - start_sample) * bytes_per_sample;
diff --git a/src/audio_provider_hd.cpp b/src/audio_provider_hd.cpp
index 48b783c74..5704eb2ec 100644
--- a/src/audio_provider_hd.cpp
+++ b/src/audio_provider_hd.cpp
@@ -52,7 +52,6 @@
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/filesystem.hpp>
-#include <fstream>
 
 namespace {
 agi::fs::path cache_dir() {
@@ -103,7 +102,7 @@ void HDAudioProvider::FillBuffer(void *buf, int64_t start, int64_t count) const
 	memcpy(buf, file->read(start, count), count);
 }
 
-void HDAudioProvider::FillCache(AudioProvider *src, std::ofstream *out, agi::ProgressSink *ps) {
+void HDAudioProvider::FillCache(AudioProvider *src, std::ostream *out, agi::ProgressSink *ps) {
 	ps->SetMessage(from_wx(_("Reading to Hard Disk cache")));
 
 	int64_t block = 65536;
diff --git a/src/audio_provider_hd.h b/src/audio_provider_hd.h
index 21c108db2..c65ede51b 100644
--- a/src/audio_provider_hd.h
+++ b/src/audio_provider_hd.h
@@ -49,7 +49,7 @@ class HDAudioProvider final : public AudioProviderWrapper {
 	/// @param src Audio data to cache
 	/// @param file File to write to
 	/// @param ps Sink for progress reporting
-	void FillCache(AudioProvider *src, std::ofstream *file, agi::ProgressSink *ps);
+	void FillCache(AudioProvider *src, std::ostream *file, agi::ProgressSink *ps);
 
 	void FillBuffer(void *buf, int64_t start, int64_t count) const override;
 
diff --git a/src/dialog_shift_times.cpp b/src/dialog_shift_times.cpp
index 4d40a1793..31c291207 100644
--- a/src/dialog_shift_times.cpp
+++ b/src/dialog_shift_times.cpp
@@ -46,7 +46,6 @@
 #include <libaegisub/cajun/writer.h>
 
 #include <algorithm>
-#include <fstream>
 #include <vector>
 
 #include <wx/listbox.h>
diff --git a/src/main.cpp b/src/main.cpp
index 5e7e924e2..f2d4291a3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -65,7 +65,6 @@
 #include <libaegisub/path.h>
 #include <libaegisub/util.h>
 
-#include <boost/filesystem/fstream.hpp>
 #include <boost/format.hpp>
 #include <boost/interprocess/streams/bufferstream.hpp>
 #include <boost/locale.hpp>
diff --git a/src/spellchecker_hunspell.cpp b/src/spellchecker_hunspell.cpp
index a1ffd1143..9eec783bc 100644
--- a/src/spellchecker_hunspell.cpp
+++ b/src/spellchecker_hunspell.cpp
@@ -34,7 +34,6 @@
 
 #include <boost/format.hpp>
 #include <boost/range/algorithm.hpp>
-#include <fstream>
 #include <hunspell/hunspell.hxx>
 
 HunspellSpellChecker::HunspellSpellChecker()
diff --git a/src/subtitle_format_ebu3264.cpp b/src/subtitle_format_ebu3264.cpp
index 8e73df9e7..ed6306134 100644
--- a/src/subtitle_format_ebu3264.cpp
+++ b/src/subtitle_format_ebu3264.cpp
@@ -39,7 +39,6 @@
 #include <libaegisub/line_wrap.h>
 
 #include <boost/algorithm/string/replace.hpp>
-#include <fstream>
 
 namespace
 {
diff --git a/src/text_file_writer.cpp b/src/text_file_writer.cpp
index d616a113a..57e6179e8 100644
--- a/src/text_file_writer.cpp
+++ b/src/text_file_writer.cpp
@@ -30,7 +30,6 @@
 
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/filesystem.hpp>
-#include <fstream>
 
 TextFileWriter::TextFileWriter(agi::fs::path const& filename, std::string encoding)
 : file(new agi::io::Save(filename, true))