diff --git a/src/modification.cc b/src/modification.cc
deleted file mode 100644
index ba22a373..00000000
--- a/src/modification.cc
+++ /dev/null
@@ -1,232 +0,0 @@
-#include "modification.hh"
-
-#include "buffer.hh"
-
-namespace Kakoune
-{
-
-namespace
-{
-
-ByteCount change_added_column(const Buffer::Change& change)
-{
-    kak_assert(change.type == Buffer::Change::Insert);
-    if (change.begin.line == change.end.line)
-        return change.end.column - change.begin.column;
-    else
-        return change.end.column;
-}
-
-}
-
-ByteCoord Modification::added_end() const
-{
-    if (num_added.line)
-        return { new_coord.line + num_added.line, num_added.column };
-    else
-        return { new_coord.line, new_coord.column + num_added.column };
-}
-
-ByteCoord Modification::removed_end() const
-{
-    if (num_removed.line)
-        return { old_coord.line + num_removed.line, num_removed.column };
-    else
-        return { old_coord.line, old_coord.column + num_removed.column };
-}
-
-ByteCoord Modification::get_old_coord(ByteCoord coord) const
-{
-    Modification inverse = { new_coord, old_coord, num_added, num_removed };
-    return inverse.get_new_coord(coord);
-}
-
-ByteCoord Modification::get_new_coord(ByteCoord coord) const
-{
-    if (coord < old_coord)
-        return coord;
-
-    // apply remove
-    if (coord < removed_end())
-        coord = old_coord;
-    else if (coord.line == old_coord.line + num_removed.line)
-    {
-        coord.line = old_coord.line;
-        if (num_removed.line != 0)
-            coord.column += old_coord.column;
-        coord.column -= num_removed.column;
-    }
-    else
-        coord.line -= num_removed.line;
-
-    // apply move
-    coord.line += new_coord.line - old_coord.line;
-    if (coord.line == new_coord.line)
-        coord.column += new_coord.column - old_coord.column;
-
-    // apply add
-    if (coord.line == new_coord.line)
-    {
-        if (num_added.line == 0)
-            coord.column += num_added.column;
-        else
-            coord.column += num_added.column - new_coord.column;
-    }
-    coord.line += num_added.line;
-
-    return coord;
-}
-
-std::vector<Modification> compute_modifications(memoryview<Buffer::Change> changes)
-{
-    std::vector<Modification> res;
-    for (auto& change : changes)
-    {
-        auto pos = std::upper_bound(res.begin(), res.end(), change.begin,
-                                    [](const ByteCoord& l, const Modification& c)
-                                    { return l < c.new_coord; });
-
-        if (pos != res.begin())
-        {
-            auto& prev = *(pos-1);
-            if (change.begin <= prev.added_end())
-                --pos;
-            else
-                pos = res.insert(pos, {prev.get_old_coord(change.begin), change.begin, {}, {}});
-        }
-        else
-            pos = res.insert(pos, {change.begin, change.begin, {}, {}});
-
-        auto& modif = *pos;
-        auto next = pos + 1;
-        if (change.type == Buffer::Change::Insert)
-        {
-            const LineCount last_line = modif.new_coord.line + modif.num_added.line;
-
-            modif.num_added.line += change.end.line - change.begin.line;
-
-            if (change.begin.line == last_line)
-            {
-                if (change.end.line == change.begin.line)
-                    modif.num_added.column += change.end.column - change.begin.column;
-                else
-                    modif.num_added.column = change.end.column;
-                kak_assert(modif.num_added.column >= 0);
-            }
-
-            for (auto it = next; it != res.end(); ++it)
-            {
-                if (it->new_coord.line == change.begin.line)
-                    it->new_coord.column += change.end.column - change.begin.column;
-                it->new_coord.line += change.end.line - change.begin.line;
-
-#ifdef KAK_DEBUG
-                auto ref_new_coord = (it-1)->get_new_coord(it->old_coord);
-                kak_assert(it->new_coord == ref_new_coord);
-#endif
-            }
-        }
-        else
-        {
-            ByteCoord num_removed = { change.end.line - change.begin.line, 0 };
-            if (num_removed.line != 0)
-                num_removed.column = change.end.column;
-            else
-                num_removed.column = change.end.column - change.begin.column;
-
-            ByteCoord num_added;
-
-            // merge modifications lying in the erased range.
-            auto delend = std::upper_bound(next, res.end(), change.end,
-                                           [](const ByteCoord& l, const Modification& c)
-                                           { return l < c.new_coord; });
-
-            for (auto it = next; it != delend; ++it)
-            {
-                {
-                    LineCount removed_from_it = change.end.line - it->new_coord.line;
-                    num_removed.line += it->num_removed.line - std::min(removed_from_it, it->num_added.line);
-                    num_added.line += std::max(0_line, it->num_added.line - removed_from_it);
-                }
-
-                if (it->new_coord.line == change.end.line)
-                    num_removed.column += it->num_removed.column;
-                if (it->new_coord.line + it->num_added.line == change.end.line)
-                {
-                    ByteCount removed_from_added = std::min(num_removed.column, it->num_added.column);
-                    num_added.column += std::max(0_byte, it->num_added.column - removed_from_added);
-                    num_removed.column -= removed_from_added;
-                }
-                if (it->new_coord.line == change.begin.line)
-                    num_removed.column += it->new_coord.column - change.begin.column;
-            }
-            next = res.erase(next, delend);
-
-            // update modification with changes
-            if (change.end.line == modif.new_coord.line + modif.num_added.line)
-            {
-                ByteCount removed_from_added = std::min(num_removed.column, modif.num_added.column);
-                modif.num_added.column = std::max(0_byte, modif.num_added.column - removed_from_added) + num_added.column;
-                modif.num_removed.column += num_removed.column - removed_from_added;
-            }
-            else if (change.end.line > modif.new_coord.line + modif.num_added.line)
-            {
-                modif.num_added.column = num_added.column;
-                modif.num_removed.column = num_removed.column;
-            }
-            if (change.begin.line == modif.new_coord.line)
-                modif.num_added.column += change.begin.column - modif.new_coord.column;
-
-            {
-                LineCount change_pos_in_modif = change.begin.line - modif.new_coord.line;
-                LineCount removed_from_added = std::min(num_removed.line, modif.num_added.line - change_pos_in_modif);
-                modif.num_added.line = std::max(0_line, modif.num_added.line - removed_from_added) + num_added.line;
-                modif.num_removed.line += num_removed.line - removed_from_added;
-            }
-
-            for (auto it = next; it != res.end(); ++it)
-            {
-                if (it->new_coord.line == change.end.line)
-                    it->new_coord.column += change.begin.column - change.end.column;
-                it->new_coord.line += change.begin.line - change.end.line;
-
-#ifdef KAK_DEBUG
-                auto ref_new_coord = (it-1)->get_new_coord(it->old_coord);
-                kak_assert(it->new_coord == ref_new_coord);
-#endif
-            }
-        }
-    }
-
-#ifdef KAK_DEBUG
-    for (size_t i = 0; i+1 < res.size(); ++i)
-    {
-        auto old_coord = res[i].get_old_coord(res[i+1].new_coord);
-        kak_assert(res[i+1].old_coord == old_coord);
-        auto new_coord = res[i].get_new_coord(res[i+1].old_coord);
-        kak_assert(res[i+1].new_coord == new_coord);
-    }
-#endif
-
-    return res;
-}
-
-std::vector<Modification> compute_modifications(const Buffer& buffer, size_t timestamp)
-{
-    return compute_modifications(buffer.changes_since(timestamp));
-}
-
-ByteCoord update_pos(memoryview<Modification> modifs, ByteCoord pos)
-{
-    auto modif_it = std::upper_bound(modifs.begin(), modifs.end(), pos,
-                                     [](const ByteCoord& c, const Modification& m)
-                                     { return c < m.old_coord; });
-    if (modif_it != modifs.begin())
-    {
-        auto& prev = *(modif_it-1);
-        return prev.get_new_coord(pos);
-    }
-    return pos;
-}
-
-}
diff --git a/src/modification.hh b/src/modification.hh
deleted file mode 100644
index 2b972a84..00000000
--- a/src/modification.hh
+++ /dev/null
@@ -1,33 +0,0 @@
-#ifndef modification_hh_INCLUDED
-#define modification_hh_INCLUDED
-
-#include "coord.hh"
-#include "utils.hh"
-#include "buffer.hh"
-
-namespace Kakoune
-{
-
-struct Modification
-{
-    ByteCoord old_coord;
-    ByteCoord new_coord;
-    ByteCoord num_removed;
-    ByteCoord num_added;
-
-    ByteCoord added_end() const;
-    ByteCoord removed_end() const;
-
-    ByteCoord get_old_coord(ByteCoord coord) const;
-    ByteCoord get_new_coord(ByteCoord coord) const;
-};
-
-std::vector<Modification> compute_modifications(const Buffer& buffer, size_t timestamp);
-std::vector<Modification> compute_modifications(memoryview<Buffer::Change> changes);
-
-ByteCoord update_pos(memoryview<Modification> modifs, ByteCoord pos);
-
-
-}
-
-#endif // modification_hh_INCLUDED
diff --git a/src/normal.cc b/src/normal.cc
index 62cfb864..2e7e166e 100644
--- a/src/normal.cc
+++ b/src/normal.cc
@@ -17,7 +17,6 @@
 #include "user_interface.hh"
 #include "utf8_iterator.hh"
 #include "debug.hh"
-#include "modification.hh"
 
 namespace Kakoune
 {
diff --git a/src/unit_tests.cc b/src/unit_tests.cc
index c7569804..85038d06 100644
--- a/src/unit_tests.cc
+++ b/src/unit_tests.cc
@@ -4,8 +4,6 @@
 #include "selectors.hh"
 #include "word_db.hh"
 
-#include "modification.hh"
-
 using namespace Kakoune;
 
 void test_buffer()
@@ -144,144 +142,6 @@ void test_keys()
     kak_assert(keys == parsed_keys);
 }
 
-void test_modification()
-{
-    {
-        Modification modif = { {5, 10}, {5, 10}, {0, 0}, {4, 17} };
-        auto pos = modif.get_new_coord({5, 10});
-        kak_assert(pos == ByteCoord{9 COMMA 17});
-    }
-    {
-        Modification modif = { {7, 10}, {7, 10}, {0, 5}, {0, 0} };
-        auto pos = modif.get_new_coord({7, 10});
-        kak_assert(pos == ByteCoord{7 COMMA 10});
-    }
-    {
-        Modification modif = { {8, 0}, {8, 0}, {1, 0}, {1, 0} };
-        auto pos = modif.get_new_coord({12, 31});
-        kak_assert(pos == ByteCoord{12 COMMA 31});
-    }
-    {
-        Modification modif = { {0, 7}, {0, 8}, {0, 0}, {0, 1} };
-        auto pos = modif.get_new_coord({1, 0});
-        kak_assert(pos == ByteCoord{1 COMMA 0});
-    }
-    {
-        std::vector<Buffer::Change> change = {
-            { Buffer::Change::Insert, {1, 0}, {5, 161}, false },
-            { Buffer::Change::Insert, {5, 161}, {30, 0}, false },
-            { Buffer::Change::Insert, {30, 0}, {35, 0}, false },
-        };
-        auto modifs = compute_modifications(change);
-        kak_assert(modifs.size() == 1);
-        auto& modif = modifs[0];
-        kak_assert(modif.old_coord == ByteCoord{1 COMMA 0});
-        kak_assert(modif.new_coord == ByteCoord{1 COMMA 0});
-        kak_assert(modif.num_added == ByteCoord{34 COMMA 0});
-        kak_assert(modif.num_removed == ByteCoord{0 COMMA 0});
-    }
-    {
-        std::vector<Buffer::Change> change = {
-            { Buffer::Change::Insert, {1, 20}, {2, 0}, false },
-            { Buffer::Change::Insert, {1, 10}, {2, 0}, false },
-            { Buffer::Change::Insert, {1, 0},  {2, 0}, false },
-        };
-        auto modifs = compute_modifications(change);
-        kak_assert(modifs.size() == 3);
-        auto& modif = modifs[2];
-        kak_assert(modif.old_coord == ByteCoord{1 COMMA 20});
-        kak_assert(modif.new_coord == ByteCoord{3 COMMA 10});
-        kak_assert(modif.num_added == ByteCoord{1 COMMA 0});
-        kak_assert(modif.num_removed == ByteCoord{0 COMMA 0});
-    }
-    {
-        std::vector<Buffer::Change> change = {
-            { Buffer::Change::Erase, {1, 10}, {2, 0}, false },
-            { Buffer::Change::Erase, {0, 10}, {1, 0}, false },
-        };
-        auto modifs = compute_modifications(change);
-        kak_assert(modifs.size() == 2);
-        auto& modif = modifs[1];
-        kak_assert(modif.old_coord == ByteCoord{1 COMMA 10});
-        kak_assert(modif.new_coord == ByteCoord{0 COMMA 20});
-        kak_assert(modif.num_added == ByteCoord{0 COMMA 0});
-        kak_assert(modif.num_removed == ByteCoord{1 COMMA 0});
-    }
-    {
-        std::vector<Buffer::Change> change = {
-            { Buffer::Change::Insert, {1, 10}, {2, 0}, false },
-            { Buffer::Change::Erase, {1, 20}, {2, 10}, false },
-        };
-        auto modifs = compute_modifications(change);
-        kak_assert(modifs.size() == 1);
-        auto& modif = modifs[0];
-        kak_assert(modif.old_coord == ByteCoord{1 COMMA 10});
-        kak_assert(modif.new_coord == ByteCoord{1 COMMA 10});
-        kak_assert(modif.num_added == ByteCoord{0 COMMA 10});
-        kak_assert(modif.num_removed == ByteCoord{0 COMMA 10});
-    }
-    {
-        std::vector<Buffer::Change> change = {
-            { Buffer::Change::Insert, {1, 10}, {2, 20}, false },
-            { Buffer::Change::Erase, {1, 5}, {2, 10}, false },
-        };
-        auto modifs = compute_modifications(change);
-        kak_assert(modifs.size() == 1);
-        auto& modif = modifs[0];
-        kak_assert(modif.old_coord == ByteCoord{1 COMMA 5});
-        kak_assert(modif.new_coord == ByteCoord{1 COMMA 5});
-        kak_assert(modif.num_added == ByteCoord{0 COMMA 10});
-        kak_assert(modif.num_removed == ByteCoord{0 COMMA 5});
-    }
-    {
-        std::vector<Buffer::Change> change = {
-            { Buffer::Change::Insert, {1, 10}, {2, 20}, false },
-            { Buffer::Change::Erase, {1, 5}, {2, 10}, false },
-            { Buffer::Change::Erase, {1, 10}, {2, 0}, false },
-        };
-        auto modifs = compute_modifications(change);
-        kak_assert(modifs.size() == 1);
-        auto& modif = modifs[0];
-        kak_assert(modif.old_coord == ByteCoord{1 COMMA 5});
-        kak_assert(modif.new_coord == ByteCoord{1 COMMA 5});
-        kak_assert(modif.num_added == ByteCoord{0 COMMA 5});
-        kak_assert(modif.num_removed == ByteCoord{1 COMMA 0});
-    }
-
-    Buffer buffer("test", Buffer::Flags::None,
-                  { "tchou mutch\n",
-                    "tchou kanaky tchou\n",
-                    "\n",
-                    "tchaa tchaa\n",
-                    "allo\n"});
-
-    size_t timestamp = buffer.timestamp();
-
-    buffer.erase(buffer.iterator_at({0,0}), buffer.iterator_at({3,0}));
-    buffer.insert(buffer.iterator_at({0,0}), "youuhou\nniahaha");
-
-    buffer.insert(buffer.iterator_at({2,4}), "yeehaah\n");
-
-    auto modifs = compute_modifications(buffer, timestamp);
-    kak_assert(modifs.size() == 2);
-    {
-        auto& modif = modifs[0];
-        kak_assert(modif.old_coord == ByteCoord{0 COMMA 0});
-        kak_assert(modif.new_coord == ByteCoord{0 COMMA 0});
-        kak_assert(modif.num_added == ByteCoord{1 COMMA 7});
-        kak_assert(modif.num_removed == ByteCoord{3 COMMA 0});
-        auto new_coord = modif.get_new_coord({1, 10});
-        kak_assert(new_coord == ByteCoord{1 COMMA 7});
-    }
-    {
-        auto& modif = modifs[1];
-        kak_assert(modif.old_coord == ByteCoord{4 COMMA 4});
-        kak_assert(modif.new_coord == ByteCoord{2 COMMA 4});
-        kak_assert(modif.num_added == ByteCoord{1 COMMA 0});
-        kak_assert(modif.num_removed == ByteCoord{0 COMMA 0});
-    }
-}
-
 void run_unit_tests()
 {
     test_utf8();
@@ -289,6 +149,5 @@ void run_unit_tests()
     test_keys();
     test_buffer();
     test_undo_group_optimizer();
-    test_modification();
     test_word_db();
 }