diff --git a/src/buffer.cc b/src/buffer.cc
index 5219f1b6e..c92f09b1b 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -39,7 +39,7 @@ Buffer::Buffer(String name, Flags flags, std::vector<String> lines,
         pos += m_lines.back().length();
     }
 
-    m_changes.push_back({ Change::Insert, {0,0}, line_count() });
+    m_changes.push_back({ Change::Insert, {0,0}, line_count(), true });
 
     if (flags & Flags::File)
     {
@@ -78,7 +78,7 @@ void Buffer::reload(std::vector<String> lines, time_t fs_timestamp)
     for (auto listener : m_change_listeners)
         listener->on_erase(*this, {0,0}, back_coord());
 
-    m_changes.push_back({ Change::Erase, {0,0}, back_coord() });
+    m_changes.push_back({ Change::Erase, {0,0}, back_coord(), true });
 
     m_history.clear();
     m_current_undo_group.clear();
@@ -99,7 +99,7 @@ void Buffer::reload(std::vector<String> lines, time_t fs_timestamp)
     }
     m_fs_timestamp = fs_timestamp;
 
-    m_changes.push_back({ Change::Insert, {0,0}, back_coord() });
+    m_changes.push_back({ Change::Insert, {0,0}, back_coord(), true });
 
     for (auto listener : m_change_listeners)
         listener->on_insert(*this, {0,0}, back_coord());
@@ -459,6 +459,7 @@ ByteCoord Buffer::do_insert(ByteCoord pos, const String& content)
 
     ByteCoord begin;
     ByteCoord end;
+    bool at_end = false;
     // if we inserted at the end of the buffer, we have created a new
     // line without inserting a '\n'
     if (is_end(pos))
@@ -477,6 +478,7 @@ ByteCoord Buffer::do_insert(ByteCoord pos, const String& content)
 
         begin = pos.column == 0 ? pos : ByteCoord{ pos.line + 1, 0 };
         end = ByteCoord{ line_count()-1, m_lines.back().length() };
+        at_end = true;
     }
     else
     {
@@ -519,7 +521,7 @@ ByteCoord Buffer::do_insert(ByteCoord pos, const String& content)
         end = ByteCoord{ last_line, m_lines[last_line].length() - suffix.length() };
     }
 
-    m_changes.push_back({ Change::Insert, begin, end });
+    m_changes.push_back({ Change::Insert, begin, end, at_end });
     for (auto listener : m_change_listeners)
         listener->on_insert(*this, begin, end);
     return begin;
@@ -550,7 +552,7 @@ ByteCoord Buffer::do_erase(ByteCoord begin, ByteCoord end)
     for (LineCount i = begin.line+1; i < line_count(); ++i)
         m_lines[i].start -= length;
 
-    m_changes.push_back({ Change::Erase, begin, end });
+    m_changes.push_back({ Change::Erase, begin, end, is_end(begin) });
     for (auto listener : m_change_listeners)
         listener->on_erase(*this, begin, end);
     return next;
diff --git a/src/buffer.hh b/src/buffer.hh
index 46b982a82..89684ce5c 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -182,6 +182,7 @@ public:
         Type type;
         ByteCoord begin;
         ByteCoord end;
+        bool at_end;
     };
     memoryview<Change> changes_since(size_t timestamp) const;
 private:
diff --git a/src/line_change_watcher.cc b/src/line_change_watcher.cc
index 2e7ba8797..c13a43b21 100644
--- a/src/line_change_watcher.cc
+++ b/src/line_change_watcher.cc
@@ -1,12 +1,57 @@
 #include "line_change_watcher.hh"
 
+#include "buffer.hh"
+
 namespace Kakoune
 {
 
+namespace
+{
+
+struct Change
+{
+    LineCount pos;
+    LineCount num;
+};
+
+std::vector<Change> compute_changes(const Buffer& buffer, size_t timestamp)
+{
+    std::vector<Change> res;
+    for (auto& change : buffer.changes_since(timestamp))
+    {
+        ByteCoord begin = change.begin;
+        ByteCoord end = change.end;
+        if (change.type == Buffer::Change::Insert)
+        {
+            if (change.at_end and begin != ByteCoord{0,0})
+            {
+                kak_assert(begin.column == 0);
+                --begin.line;
+            }
+            res.push_back({begin.line, end.line - begin.line});
+        }
+        else
+        {
+            if (change.at_end and begin != ByteCoord{0,0})
+            {
+                kak_assert(begin.column == 0);
+                --begin.line;
+            }
+            res.push_back({begin.line, begin.line - end.line});
+        }
+    }
+    return res;
+}
+
+}
+
+LineChangeWatcher::LineChangeWatcher(const Buffer& buffer)
+    : m_buffer(&buffer), m_timestamp(buffer.timestamp()) {}
+
 std::vector<LineModification> LineChangeWatcher::compute_modifications()
 {
     std::vector<LineModification> res;
-    for (auto& change : m_changes)
+    for (auto& change : compute_changes(*m_buffer, m_timestamp))
     {
         auto pos = std::upper_bound(res.begin(), res.end(), change.pos,
                                     [](const LineCount& l, const LineModification& c)
@@ -58,28 +103,8 @@ std::vector<LineModification> LineChangeWatcher::compute_modifications()
                 it->new_line -= num_removed;
         }
     }
-    m_changes.clear();
+    m_timestamp = m_buffer->timestamp();
     return res;
 }
 
-void LineChangeWatcher::on_insert(const Buffer& buffer, ByteCoord begin, ByteCoord end)
-{
-    if (buffer.is_end(end))
-    {
-        kak_assert(begin.column == 0);
-        --begin.line;
-    }
-    m_changes.push_back({begin.line, end.line - begin.line});
-}
-
-void LineChangeWatcher::on_erase(const Buffer& buffer, ByteCoord begin, ByteCoord end)
-{
-    if (begin.line == buffer.line_count())
-    {
-        kak_assert(begin.column == 0);
-        --begin.line;
-    }
-    m_changes.push_back({begin.line, begin.line - end.line});
-}
-
 }
diff --git a/src/line_change_watcher.hh b/src/line_change_watcher.hh
index ce7bedfa0..d35167cae 100644
--- a/src/line_change_watcher.hh
+++ b/src/line_change_watcher.hh
@@ -1,11 +1,14 @@
 #ifndef line_change_watcher_hh_INCLUDED
 #define line_change_watcher_hh_INCLUDED
 
-#include "buffer.hh"
+#include "units.hh"
+#include "utils.hh"
 
 namespace Kakoune
 {
 
+class Buffer;
+
 struct LineModification
 {
     LineCount old_line; // line position in the old buffer
@@ -16,23 +19,17 @@ struct LineModification
     LineCount diff() const { return new_line - old_line + num_added - num_removed; }
 };
 
-class LineChangeWatcher : public BufferChangeListener_AutoRegister
+class LineChangeWatcher
 {
 public:
-    LineChangeWatcher (const Buffer& buffer)
-        : BufferChangeListener_AutoRegister(const_cast<Buffer&>(buffer)) {}
+    LineChangeWatcher (const Buffer& buffer);
 
     std::vector<LineModification> compute_modifications();
-private:
-    void on_insert(const Buffer& buffer, ByteCoord begin, ByteCoord end) override;
-    void on_erase(const Buffer& buffer, ByteCoord begin, ByteCoord end) override;
 
-    struct Change
-    {
-        LineCount pos;
-        LineCount num;
-    };
-    std::vector<Change> m_changes;
+    const Buffer& buffer() const { return *m_buffer; }
+private:
+    safe_ptr<const Buffer> m_buffer;
+    size_t m_timestamp;
 };
 
 }
diff --git a/src/word_db.cc b/src/word_db.cc
index 62e19290c..73f6e1ad7 100644
--- a/src/word_db.cc
+++ b/src/word_db.cc
@@ -65,7 +65,7 @@ void WordDB::update_db()
     if (modifs.empty())
         return;
 
-    auto& buffer = m_change_watcher.registry();
+    auto& buffer = m_change_watcher.buffer();
 
     LineToWords new_lines;
     new_lines.reserve((int)buffer.line_count());