diff --git a/src/buffer.cc b/src/buffer.cc
index 266d4905..d94c5617 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -256,9 +256,9 @@ void Buffer::do_insert(const BufferIterator& pos, const String& content)
 
     BufferIterator begin_it;
     BufferIterator end_it;
-    // if we inserted at the end of the buffer, we may have created a new
+    // if we inserted at the end of the buffer, we have created a new
     // line without inserting a '\n'
-    if (pos == end() and (pos == begin() or *(pos-1) == '\n'))
+    if (pos.is_end())
     {
         ByteCount start = 0;
         for (ByteCount i = 0; i < content.length(); ++i)
@@ -361,7 +361,7 @@ void Buffer::apply_modification(const Modification& modification)
     {
     case Modification::Insert:
     {
-        do_insert(pos < end() ? pos : end(), content);
+        do_insert(pos, content);
         break;
     }
     case Modification::Erase:
diff --git a/src/buffer_iterator.inl.hh b/src/buffer_iterator.inl.hh
index 201ea481..1e477561 100644
--- a/src/buffer_iterator.inl.hh
+++ b/src/buffer_iterator.inl.hh
@@ -116,8 +116,7 @@ inline char BufferIterator::operator*() const
 inline ByteCount BufferIterator::offset() const
 {
     assert(m_buffer);
-    return line() == 0 ? column()
-                       : m_buffer->m_lines[line()].start + column();
+    return m_buffer->m_lines[line()].start + column();
 }
 
 inline size_t BufferIterator::operator-(const BufferIterator& iterator) const
@@ -221,6 +220,11 @@ inline bool BufferIterator::is_begin() const
 inline bool BufferIterator::is_end() const
 {
     assert(m_buffer);
+    if (m_coord.line == m_buffer->line_count())
+    {
+        assert(m_coord.column == 0);
+        return true;
+    }
     return offset() == m_buffer->character_count();
 }