diff --git a/src/buffer.cc b/src/buffer.cc
index b0e70748..22f4a794 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -158,6 +158,12 @@ bool Buffer::set_name(String name)
     return false;
 }
 
+void Buffer::throw_if_read_only() const
+{
+    if (m_flags & Flags::ReadOnly)
+        throw runtime_error("Buffer is read-only");
+}
+
 void Buffer::update_display_name()
 {
     if (m_flags & Flags::File)
@@ -315,8 +321,10 @@ void Buffer::commit_undo_group()
     m_history_cursor = node;
 }
 
-bool Buffer::undo(size_t count) noexcept
+bool Buffer::undo(size_t count)
 {
+    throw_if_read_only();
+
     commit_undo_group();
 
     if (not m_history_cursor->parent)
@@ -333,8 +341,10 @@ bool Buffer::undo(size_t count) noexcept
     return true;
 }
 
-bool Buffer::redo(size_t count) noexcept
+bool Buffer::redo(size_t count)
 {
+    throw_if_read_only();
+
     if (not m_history_cursor->redo_child)
         return false;
 
@@ -350,8 +360,10 @@ bool Buffer::redo(size_t count) noexcept
     return true;
 }
 
-void Buffer::move_to(HistoryNode* history_node) noexcept
+void Buffer::move_to(HistoryNode* history_node)
 {
+    throw_if_read_only();
+
     commit_undo_group();
 
     auto find_lowest_common_parent = [](HistoryNode* a, HistoryNode* b) {
@@ -419,7 +431,7 @@ Buffer::HistoryNode* Buffer::find_history_node(HistoryNode* node, const Func& fu
     return nullptr;
 }
 
-bool Buffer::move_to(size_t history_id) noexcept
+bool Buffer::move_to(size_t history_id)
 {
     auto* target_node = find_history_node(&m_history, [history_id](auto* node)
                                           { return node->id == history_id; });
@@ -548,6 +560,8 @@ void Buffer::apply_modification(const Modification& modification)
 
 BufferCoord Buffer::insert(BufferCoord pos, StringView content)
 {
+    throw_if_read_only();
+
     kak_assert(is_valid(pos));
     if (content.empty())
         return pos;
@@ -568,6 +582,8 @@ BufferCoord Buffer::insert(BufferCoord pos, StringView content)
 
 BufferCoord Buffer::erase(BufferCoord begin, BufferCoord end)
 {
+    throw_if_read_only();
+
     kak_assert(is_valid(begin) and is_valid(end));
     // do not erase last \n except if we erase from the start of a line, and normalize
     // end coord
@@ -585,6 +601,8 @@ BufferCoord Buffer::erase(BufferCoord begin, BufferCoord end)
 
 BufferCoord Buffer::replace(BufferCoord begin, BufferCoord end, StringView content)
 {
+    throw_if_read_only();
+
     if (is_end(end) and not content.empty() and content.back() == '\n')
     {
         end = back_coord();
diff --git a/src/buffer.hh b/src/buffer.hh
index 0eb6a4f4..d8f18015 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -139,9 +139,9 @@ public:
     void           set_fs_timestamp(timespec ts);
 
     void           commit_undo_group();
-    bool           undo(size_t count = 1) noexcept;
-    bool           redo(size_t count = 1) noexcept;
-    bool           move_to(size_t history_id) noexcept;
+    bool           undo(size_t count = 1);
+    bool           redo(size_t count = 1);
+    bool           move_to(size_t history_id);
     size_t         current_history_id() const noexcept;
     size_t         next_history_id() const noexcept { return m_next_history_id; }
 
@@ -218,6 +218,7 @@ public:
     void on_registered();
     void on_unregistered();
 
+    void throw_if_read_only() const;
 private:
     void on_option_changed(const Option& option) override;
 
@@ -272,7 +273,7 @@ private:
     SafePtr<HistoryNode>  m_last_save_history_cursor;
     UndoGroup             m_current_undo_group;
 
-    void move_to(HistoryNode* history_node) noexcept;
+    void move_to(HistoryNode* history_node);
 
     template<typename Func> HistoryNode* find_history_node(HistoryNode* node, const Func& func);
 
diff --git a/src/buffer_utils.cc b/src/buffer_utils.cc
index 1e282695..4a6e3816 100644
--- a/src/buffer_utils.cc
+++ b/src/buffer_utils.cc
@@ -181,12 +181,17 @@ void write_to_debug_buffer(StringView str)
     // where the user can put its cursor to scroll with new messages
     const bool eol_back = not str.empty() and str.back() == '\n';
     if (Buffer* buffer = BufferManager::instance().get_buffer_ifp(debug_buffer_name))
+    {
+        buffer->flags() &= ~Buffer::Flags::ReadOnly;
+        auto restore = on_scope_end([buffer] { buffer->flags() |= Buffer::Flags::ReadOnly; });
+
         buffer->insert(buffer->back_coord(), eol_back ? str : str + "\n");
+    }
     else
     {
         String line = str + (eol_back ? "\n" : "\n\n");
         BufferManager::instance().create_buffer(
-            debug_buffer_name.str(), Buffer::Flags::NoUndo | Buffer::Flags::Debug,
+            debug_buffer_name.str(), Buffer::Flags::NoUndo | Buffer::Flags::Debug | Buffer::Flags::ReadOnly,
             line, InvalidTime);
     }
 }
diff --git a/src/input_handler.cc b/src/input_handler.cc
index f8211a2e..3662e12f 100644
--- a/src/input_handler.cc
+++ b/src/input_handler.cc
@@ -1061,6 +1061,8 @@ public:
                            context().hooks().run_hook("InsertIdle", "", context());
                        }}
     {
+        context().buffer().throw_if_read_only();
+
         last_insert().recording.set();
         last_insert().mode = mode;
         last_insert().keys.clear();
@@ -1068,11 +1070,6 @@ public:
         last_insert().count = count;
         context().hooks().run_hook("InsertBegin", "", context());
         prepare(mode, count);
-
-        if (context().has_client() and
-            context().options()["readonly"].get<bool>())
-            context().print_status({ "Warning: This buffer is readonly",
-                                     get_face("Error") });
     }
 
     void on_enabled() override