diff --git a/src/Box.cpp b/src/Box.cpp
index a3461ef3ea..28d2caa01c 100644
--- a/src/Box.cpp
+++ b/src/Box.cpp
@@ -31,7 +31,7 @@ Box::Box(int x1_, int x2_, int y1_, int y2_)
 {}
 
 
-bool Box::contains(int x, int y)
+bool Box::contains(int x, int y) const
 {
 	return (x1 < x && x2 > x && y1 < y && y2 > y);
 }
diff --git a/src/Box.h b/src/Box.h
index c362fa6a38..9522ad0a79 100644
--- a/src/Box.h
+++ b/src/Box.h
@@ -42,7 +42,7 @@ public:
 	 * the box. Check is exclusive (point on a border
 	 * returns false).
 	 */
-	bool contains(int x, int y);
+	bool contains(int x, int y) const;
 };
 
 
diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index 9ba2373ea4..d25aa03fb8 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -1610,7 +1610,7 @@ bool Buffer::writeFile(FileName const & fname) const
 }
 
 
-docstring Buffer::emergencyWrite()
+docstring Buffer::emergencyWrite() const
 {
 	// No need to save if the buffer has not changed.
 	if (isClean())
diff --git a/src/Buffer.h b/src/Buffer.h
index f65d31d654..a917c6e9f7 100644
--- a/src/Buffer.h
+++ b/src/Buffer.h
@@ -259,7 +259,7 @@ public:
 	bool autoSave() const;
 	/// save emergency file
 	/// \return a status message towards the user.
-	docstring emergencyWrite();
+	docstring emergencyWrite() const;
 
 //FIXME:The following function should be private
 //private:
diff --git a/src/Compare.cpp b/src/Compare.cpp
index 49bdac1bfa..51a28f16ec 100644
--- a/src/Compare.cpp
+++ b/src/Compare.cpp
@@ -107,7 +107,7 @@ public:
 		: o(o_), n(n_)
 	{}
 
-	bool operator!=(DocPair const & rhs)
+	bool operator!=(DocPair const & rhs) const
 	{
 		// this might not be intuitive but correct for our purpose
 		return o != rhs.o && n != rhs.n;
diff --git a/src/Converter.cpp b/src/Converter.cpp
index ada329e5d9..747dd88ada 100644
--- a/src/Converter.cpp
+++ b/src/Converter.cpp
@@ -259,7 +259,7 @@ void Converters::updateLast(Formats const & formats)
 
 
 OutputParams::FLAVOR Converters::getFlavor(Graph::EdgePath const & path,
-					   Buffer const * buffer)
+					   Buffer const * buffer) const
 {
 	for (auto const & edge : path) {
 		Converter const & conv = converterlist_[edge];
@@ -283,7 +283,7 @@ OutputParams::FLAVOR Converters::getFlavor(Graph::EdgePath const & path,
 }
 
 
-string Converters::getHyperrefDriver(Graph::EdgePath const & path)
+string Converters::getHyperrefDriver(Graph::EdgePath const & path) const
 {
 	for (auto const & edge : path) {
 		Converter const & conv = converterlist_[edge];
@@ -818,7 +818,7 @@ bool Converters::move(string const & fmt,
 }
 
 
-bool Converters::formatIsUsed(string const & format)
+bool Converters::formatIsUsed(string const & format) const
 {
 	for (auto const & cvt : converterlist_) {
 		if (cvt.from() == format || cvt.to() == format)
diff --git a/src/Converter.h b/src/Converter.h
index e9efa00f4f..b9ee3292bb 100644
--- a/src/Converter.h
+++ b/src/Converter.h
@@ -176,9 +176,9 @@ public:
 	Graph::EdgePath getPath(std::string const & from, std::string const & to);
 	///
 	OutputParams::FLAVOR getFlavor(Graph::EdgePath const & path,
-					   Buffer const * buffer = nullptr);
+					   Buffer const * buffer = nullptr) const;
 	///
-	std::string getHyperrefDriver(Graph::EdgePath const & path);
+	std::string getHyperrefDriver(Graph::EdgePath const & path) const;
 	/// Flags for converting files
 	enum ConversionFlags {
 		/// No special flags
@@ -199,7 +199,7 @@ public:
 	///
 	void updateLast(Formats const & formats);
 	///
-	bool formatIsUsed(std::string const & format);
+	bool formatIsUsed(std::string const & format) const;
 	///
 	const_iterator begin() const { return converterlist_.begin(); }
 	///
diff --git a/src/Cursor.cpp b/src/Cursor.cpp
index 7197b91cf2..9e7867c8d3 100644
--- a/src/Cursor.cpp
+++ b/src/Cursor.cpp
@@ -502,7 +502,7 @@ void CursorData::clearSelection()
 }
 
 
-int CursorData::countInsetsInSelection(InsetCode const & inset_code)
+int CursorData::countInsetsInSelection(InsetCode const & inset_code) const
 {
 	if (!selection_)
 		return 0;
@@ -528,7 +528,7 @@ int CursorData::countInsetsInSelection(InsetCode const & inset_code)
 }
 
 
-bool CursorData::insetInSelection(InsetCode const & inset_code)
+bool CursorData::insetInSelection(InsetCode const & inset_code) const
 {
 	if (!selection_)
 		return false;
@@ -669,7 +669,7 @@ void CursorData::recordUndoSelection() const
 }
 
 
-int CursorData::currentMode()
+int CursorData::currentMode() const
 {
 	LASSERT(!empty(), return Inset::UNDECIDED_MODE);
 	for (int i = depth() - 1; i >= 0; --i) {
diff --git a/src/Cursor.h b/src/Cursor.h
index fc4daeb93b..951a0cc4db 100644
--- a/src/Cursor.h
+++ b/src/Cursor.h
@@ -118,7 +118,7 @@ public:
 	///
 	void setWordSelection(bool set) { word_selection_ = set; }
 	///
-	bool wordSelection() { return word_selection_; }
+	bool wordSelection() const { return word_selection_; }
 	/// did we place the anchor?
 	bool mark() const { return mark_; }
 	/// did we place the anchor?
@@ -131,10 +131,10 @@ public:
 	void clearSelection();
 	/// check whether selection contains specific type of inset
 	/// returns 0 if no selection was made
-	bool insetInSelection(InsetCode const & inset);
+	bool insetInSelection(InsetCode const & inset) const;
 	/// count occurences of specific inset type in the selection
 	/// returns 0 if no selection was made
-	int countInsetsInSelection(InsetCode const & inset);
+	int countInsetsInSelection(InsetCode const & inset) const;
 
 	/// access to normalized selection anchor
 	CursorSlice normalAnchor() const;
@@ -207,7 +207,7 @@ public:
 	DocIterator newWord() const { return new_word_; }
 
 	/// are we in math mode (2), text mode (1) or unsure (0)?
-	int currentMode();
+	int currentMode() const;
 
 	/// Return true if the next or previous inset has confirmDeletion depending
 	/// on the boolean before. If there is a selection, return true if at least
diff --git a/src/DispatchResult.h b/src/DispatchResult.h
index d8689898d8..ac1eb6c821 100644
--- a/src/DispatchResult.h
+++ b/src/DispatchResult.h
@@ -48,7 +48,7 @@ public:
 	///
 	void setError(bool e) { error_ = e; }
 	///
-	docstring message() { return message_; }
+	docstring message() const { return message_; }
 	///
 	void setMessage(docstring const & m) { message_ = m; }
 	///
diff --git a/src/FuncRequest.h b/src/FuncRequest.h
index 42829ae8de..19f571a091 100644
--- a/src/FuncRequest.h
+++ b/src/FuncRequest.h
@@ -86,7 +86,7 @@ public:
 	///
 	mouse_button::state button() const { return button_; }
 	///
-	KeyModifier modifier() { return modifier_; }
+	KeyModifier modifier() const { return modifier_; }
 
 	/// argument parsing, extract argument i as std::string
 	std::string getArg(unsigned int i) const;
diff --git a/src/LaTeX.h b/src/LaTeX.h
index c57b03b830..994fbe07ff 100644
--- a/src/LaTeX.h
+++ b/src/LaTeX.h
@@ -185,7 +185,7 @@ public:
 	int run(TeXErrors &);
 
 	///
-	int getNumErrors() { return num_errors;}
+	int getNumErrors() const { return num_errors;}
 
 	///
 	int scanLogFile(TeXErrors &);
diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index 6578e2a19c..4ade252e72 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -359,19 +359,19 @@ public:
 		char_type const c,
 		otexstream & os,
 		pos_type i,
-		unsigned int & column);
+		unsigned int & column) const;
 	///
 	bool latexSpecialTU(
 		char_type const c,
 		otexstream & os,
 		pos_type i,
-		unsigned int & column);
+		unsigned int & column) const;
 	///
 	bool latexSpecialT3(
 		char_type const c,
 		otexstream & os,
 		pos_type i,
-		unsigned int & column);
+		unsigned int & column) const;
 
 	///
 	void validate(LaTeXFeatures & features) const;
@@ -1316,7 +1316,7 @@ void Paragraph::Private::latexSpecialChar(otexstream & os,
 
 
 bool Paragraph::Private::latexSpecialT1(char_type const c, otexstream & os,
-	pos_type i, unsigned int & column)
+	pos_type i, unsigned int & column) const
 {
 	switch (c) {
 	case '>':
@@ -1344,7 +1344,7 @@ bool Paragraph::Private::latexSpecialT1(char_type const c, otexstream & os,
 
 
 bool Paragraph::Private::latexSpecialTU(char_type const c, otexstream & os,
-	pos_type i, unsigned int & column)
+	pos_type i, unsigned int & column) const
 {
 	// TU encoding is currently on par with T1.
 	return latexSpecialT1(c, os, i, column);
@@ -1352,7 +1352,7 @@ bool Paragraph::Private::latexSpecialTU(char_type const c, otexstream & os,
 
 
 bool Paragraph::Private::latexSpecialT3(char_type const c, otexstream & os,
-	pos_type /*i*/, unsigned int & column)
+	pos_type /*i*/, unsigned int & column) const
 {
 	switch (c) {
 	case '*':
diff --git a/src/Server.h b/src/Server.h
index 40021daa41..e20406a6d4 100644
--- a/src/Server.h
+++ b/src/Server.h
@@ -104,7 +104,7 @@ public:
 #endif
 
 	/// Tell whether we asked another instance of LyX to open the files
-	bool deferredLoading() { return deferred_loading_; }
+	bool deferredLoading() const { return deferred_loading_; }
 
 private:
 	/// the filename of the in pipe
diff --git a/src/TocBackend.cpp b/src/TocBackend.cpp
index 500d5e3ce0..d9ed95767a 100644
--- a/src/TocBackend.cpp
+++ b/src/TocBackend.cpp
@@ -153,7 +153,7 @@ TocBuilder & TocBackend::builder(string const & type)
 // TocItem creation and update should be made in a dedicated function and
 // updateItem should be rewritten to uniformly update the matching items from
 // all TOCs.
-bool TocBackend::updateItem(DocIterator const & dit_in)
+bool TocBackend::updateItem(DocIterator const & dit_in) const
 {
 	// we need a text
 	DocIterator dit = dit_in.getInnerText();
diff --git a/src/TocBackend.h b/src/TocBackend.h
index 026f4f879b..b67ee60da3 100644
--- a/src/TocBackend.h
+++ b/src/TocBackend.h
@@ -116,7 +116,7 @@ public:
 	///
 	void reset();
 	/// \return true if the item was updated.
-	bool updateItem(DocIterator const & pit);
+	bool updateItem(DocIterator const & pit) const;
 	///
 	TocList const & tocs() const { return tocs_; }
 	/// never null
diff --git a/src/frontends/WorkAreaManager.cpp b/src/frontends/WorkAreaManager.cpp
index c79f08bef7..0d1d189cf2 100644
--- a/src/frontends/WorkAreaManager.cpp
+++ b/src/frontends/WorkAreaManager.cpp
@@ -47,7 +47,7 @@ void WorkAreaManager::closeAll()
 }
 
 
-bool WorkAreaManager::unhide(Buffer * buf)
+bool WorkAreaManager::unhide(Buffer * buf) const
 {
 	if (!work_areas_.empty())
 		return true;
diff --git a/src/frontends/WorkAreaManager.h b/src/frontends/WorkAreaManager.h
index 0434074ab4..cd716fc087 100644
--- a/src/frontends/WorkAreaManager.h
+++ b/src/frontends/WorkAreaManager.h
@@ -46,7 +46,7 @@ public:
 	void updateTitles();
 	/// If there is no work area, create a new one in the current view using the
 	/// buffer buf. Returns false if not possible.
-	bool unhide(Buffer * buf);
+	bool unhide(Buffer * buf) const;
 
 private:
 	typedef std::list<WorkArea *>::iterator iterator;
diff --git a/src/mathed/MacroTable.h b/src/mathed/MacroTable.h
index e83be84b75..b588ee2cf9 100644
--- a/src/mathed/MacroTable.h
+++ b/src/mathed/MacroTable.h
@@ -73,7 +73,7 @@ public:
 	///
 	void setSymbol(latexkeys const * sym) { sym_ = sym; }
 	///
-	DocIterator const & pos() { return pos_; }
+	DocIterator const & pos() const { return pos_; }
 
 	/// lock while being drawn to avoid recursions
 	int lock() const { return ++lockCount_; }
diff --git a/src/tex2lyx/Parser.cpp b/src/tex2lyx/Parser.cpp
index 62cab06fba..57253650f7 100644
--- a/src/tex2lyx/Parser.cpp
+++ b/src/tex2lyx/Parser.cpp
@@ -443,7 +443,7 @@ void Parser::dropPosition()
 }
 
 
-bool Parser::good()
+bool Parser::good() const
 {
 	if (pos_ < tokens_.size())
 		return true;
diff --git a/src/tex2lyx/Parser.h b/src/tex2lyx/Parser.h
index ada6b5f72a..41384599c2 100644
--- a/src/tex2lyx/Parser.h
+++ b/src/tex2lyx/Parser.h
@@ -334,7 +334,7 @@ public:
 	/// Is any further input pending()? This is not like
 	/// std::istream::good(), which returns true if all available input
 	/// was read, and the next attempt to read would return EOF.
-	bool good();
+	bool good() const;
 	/// resets the parser to initial state
 	void reset();