diff --git a/src/highlighters.cc b/src/highlighters.cc
index cc484b88..f3f2af60 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -5,7 +5,7 @@
 #include "color_registry.hh"
 #include "context.hh"
 #include "display_buffer.hh"
-#include "line_change_watcher.hh"
+#include "line_modification.hh"
 #include "option_types.hh"
 #include "register_manager.hh"
 #include "string.hh"
@@ -158,7 +158,7 @@ struct BufferSideCache
     {
         Value& cache_val = buffer.values()[m_id];
         if (not cache_val)
-            cache_val = Value(T{buffer});
+            cache_val = Value(T{});
         return cache_val.as<T>();
     }
 private:
@@ -195,7 +195,6 @@ public:
 private:
     struct Cache
     {
-        Cache(const Buffer&){}
         BufferRange m_range;
         size_t      m_timestamp = 0;
         std::vector<std::vector<std::pair<ByteCoord, ByteCoord>>> m_matches;
@@ -671,10 +670,8 @@ private:
                                       : lhs.begin < rhs.begin;
     }
 
-    struct Cache : public LineChangeWatcher
+    struct Cache
     {
-        Cache(const Buffer& buffer) : LineChangeWatcher(buffer) {}
-
         size_t timestamp = 0;
         MatchList begin_matches;
         MatchList end_matches;
@@ -696,7 +693,7 @@ private:
         }
         else
         {
-            auto modifs = cache.compute_modifications();
+            auto modifs = compute_line_modifications(buffer, cache.timestamp);
             update_matches(buffer, modifs, cache.begin_matches, m_begin);
             update_matches(buffer, modifs, cache.end_matches, m_end);
         }
@@ -718,7 +715,7 @@ private:
             beg_it = std::upper_bound(beg_it, cache.begin_matches.end(),
                                       *end_it, compare_matches_end);
         }
-        cache.timestamp = buffer.timestamp();
+        cache.timestamp = buf_timestamp;
         return cache.regions;
     }
 
diff --git a/src/line_change_watcher.cc b/src/line_modification.cc
similarity index 89%
rename from src/line_change_watcher.cc
rename to src/line_modification.cc
index 1a91f053..5da287fc 100644
--- a/src/line_change_watcher.cc
+++ b/src/line_modification.cc
@@ -1,4 +1,4 @@
-#include "line_change_watcher.hh"
+#include "line_modification.hh"
 
 #include "buffer.hh"
 
@@ -42,13 +42,10 @@ struct LineChange
 
 }
 
-LineChangeWatcher::LineChangeWatcher(const Buffer& buffer)
-    : m_buffer(&buffer), m_timestamp(buffer.timestamp()) {}
-
-std::vector<LineModification> LineChangeWatcher::compute_modifications()
+std::vector<LineModification> compute_line_modifications(const Buffer& buffer, size_t timestamp)
 {
     std::vector<LineModification> res;
-    for (auto& buf_change : m_buffer->changes_since(m_timestamp))
+    for (auto& buf_change : buffer.changes_since(timestamp))
     {
         const LineChange change(buf_change);
 
@@ -102,7 +99,6 @@ std::vector<LineModification> LineChangeWatcher::compute_modifications()
                 it->new_line -= num_removed;
         }
     }
-    m_timestamp = m_buffer->timestamp();
     return res;
 }
 
diff --git a/src/line_change_watcher.hh b/src/line_modification.hh
similarity index 67%
rename from src/line_change_watcher.hh
rename to src/line_modification.hh
index d35167ca..3cd2d669 100644
--- a/src/line_change_watcher.hh
+++ b/src/line_modification.hh
@@ -19,18 +19,7 @@ struct LineModification
     LineCount diff() const { return new_line - old_line + num_added - num_removed; }
 };
 
-class LineChangeWatcher
-{
-public:
-    LineChangeWatcher (const Buffer& buffer);
-
-    std::vector<LineModification> compute_modifications();
-
-    const Buffer& buffer() const { return *m_buffer; }
-private:
-    safe_ptr<const Buffer> m_buffer;
-    size_t m_timestamp;
-};
+std::vector<LineModification> compute_line_modifications(const Buffer& buffer, size_t timestamp);
 
 }
 
diff --git a/src/word_db.cc b/src/word_db.cc
index 73f6e1ad..83b362c5 100644
--- a/src/word_db.cc
+++ b/src/word_db.cc
@@ -1,6 +1,7 @@
 #include "word_db.hh"
 
 #include "utils.hh"
+#include "line_modification.hh"
 #include "utf8_iterator.hh"
 
 namespace Kakoune
@@ -49,7 +50,7 @@ static void remove_words(WordDB::WordList& wl, const std::vector<String>& words)
 }
 
 WordDB::WordDB(const Buffer& buffer)
-    : m_change_watcher{buffer}
+    : m_buffer{&buffer}, m_timestamp{buffer.timestamp()}
 {
     m_line_to_words.reserve((int)buffer.line_count());
     for (auto line = 0_line, end = buffer.line_count(); line < end; ++line)
@@ -61,11 +62,14 @@ WordDB::WordDB(const Buffer& buffer)
 
 void WordDB::update_db()
 {
-    auto modifs = m_change_watcher.compute_modifications();
+    auto& buffer = *m_buffer;
+
+    auto modifs = compute_line_modifications(buffer, m_timestamp);
+    m_timestamp = buffer.timestamp();
+
     if (modifs.empty())
         return;
 
-    auto& buffer = m_change_watcher.buffer();
 
     LineToWords new_lines;
     new_lines.reserve((int)buffer.line_count());
diff --git a/src/word_db.hh b/src/word_db.hh
index 950cc05d..2349a618 100644
--- a/src/word_db.hh
+++ b/src/word_db.hh
@@ -2,7 +2,6 @@
 #define word_db_hh_INCLUDED
 
 #include "buffer.hh"
-#include "line_change_watcher.hh"
 
 #include <map>
 
@@ -26,7 +25,8 @@ private:
 
     void update_db();
 
-    LineChangeWatcher m_change_watcher;
+    safe_ptr<const Buffer> m_buffer;
+    size_t m_timestamp;
     WordList m_words;
     LineToWords m_line_to_words;
 };