diff --git a/src/buffer.hh b/src/buffer.hh
index bfdda041..d0fdffcb 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -59,18 +59,18 @@ public:
     // costly, so this is not strictly random access
     using iterator_category = std::bidirectional_iterator_tag;
 
-    BufferIterator() : m_buffer(nullptr) {}
-    BufferIterator(const Buffer& buffer, BufferCoord coord);
+    BufferIterator() noexcept : m_buffer(nullptr) {}
+    BufferIterator(const Buffer& buffer, BufferCoord coord) noexcept;
 
-    bool operator== (const BufferIterator& iterator) const;
-    bool operator!= (const BufferIterator& iterator) const;
-    bool operator<  (const BufferIterator& iterator) const;
-    bool operator<= (const BufferIterator& iterator) const;
-    bool operator>  (const BufferIterator& iterator) const;
-    bool operator>= (const BufferIterator& iterator) const;
+    bool operator== (const BufferIterator& iterator) const noexcept;
+    bool operator!= (const BufferIterator& iterator) const noexcept;
+    bool operator<  (const BufferIterator& iterator) const noexcept;
+    bool operator<= (const BufferIterator& iterator) const noexcept;
+    bool operator>  (const BufferIterator& iterator) const noexcept;
+    bool operator>= (const BufferIterator& iterator) const noexcept;
 
-    const char& operator* () const;
-    const char& operator[](size_t n) const;
+    const char& operator* () const noexcept;
+    const char& operator[](size_t n) const noexcept;
     size_t operator- (const BufferIterator& iterator) const;
 
     BufferIterator operator+ (ByteCount size) const;
@@ -85,7 +85,7 @@ public:
     BufferIterator operator++ (int);
     BufferIterator operator-- (int);
 
-    const BufferCoord& coord() const { return m_coord; }
+    const BufferCoord& coord() const noexcept { return m_coord; }
 
 private:
     SafePtr<const Buffer> m_buffer;
diff --git a/src/buffer.inl.hh b/src/buffer.inl.hh
index d94ea42c..7d987c26 100644
--- a/src/buffer.inl.hh
+++ b/src/buffer.inl.hh
@@ -114,55 +114,52 @@ inline BufferCoord Buffer::end_coord() const
         BufferCoord{0,0} : BufferCoord{ line_count() - 1, m_lines.back().length() };
 }
 
-inline BufferIterator::BufferIterator(const Buffer& buffer, BufferCoord coord)
+inline BufferIterator::BufferIterator(const Buffer& buffer, BufferCoord coord) noexcept
     : m_buffer(&buffer), m_coord(coord),
       m_line((*m_buffer)[coord.line]),
-      m_last_line(buffer.line_count()-1)
-{
-    kak_assert(m_buffer and m_buffer->is_valid(m_coord));
-}
+      m_last_line(buffer.line_count()-1) {}
 
-inline bool BufferIterator::operator==(const BufferIterator& iterator) const
+inline bool BufferIterator::operator==(const BufferIterator& iterator) const noexcept
 {
     return m_buffer == iterator.m_buffer and m_coord == iterator.m_coord;
 }
 
-inline bool BufferIterator::operator!=(const BufferIterator& iterator) const
+inline bool BufferIterator::operator!=(const BufferIterator& iterator) const noexcept
 {
     return m_buffer != iterator.m_buffer or m_coord != iterator.m_coord;
 }
 
-inline bool BufferIterator::operator<(const BufferIterator& iterator) const
+inline bool BufferIterator::operator<(const BufferIterator& iterator) const noexcept
 {
     kak_assert(m_buffer == iterator.m_buffer);
     return (m_coord < iterator.m_coord);
 }
 
-inline bool BufferIterator::operator<=(const BufferIterator& iterator) const
+inline bool BufferIterator::operator<=(const BufferIterator& iterator) const noexcept
 {
     kak_assert(m_buffer == iterator.m_buffer);
     return (m_coord <= iterator.m_coord);
 }
 
-inline bool BufferIterator::operator>(const BufferIterator& iterator) const
+inline bool BufferIterator::operator>(const BufferIterator& iterator) const noexcept
 {
     kak_assert(m_buffer == iterator.m_buffer);
     return (m_coord > iterator.m_coord);
 }
 
-inline bool BufferIterator::operator>=(const BufferIterator& iterator) const
+inline bool BufferIterator::operator>=(const BufferIterator& iterator) const noexcept
 {
     kak_assert(m_buffer == iterator.m_buffer);
     return (m_coord >= iterator.m_coord);
 }
 
 [[gnu::always_inline]]
-inline const char& BufferIterator::operator*() const
+inline const char& BufferIterator::operator*() const noexcept
 {
     return m_line[m_coord.column];
 }
 
-inline const char& BufferIterator::operator[](size_t n) const
+inline const char& BufferIterator::operator[](size_t n) const noexcept
 {
     return m_buffer->byte_at(m_buffer->advance(m_coord, n));
 }