diff --git a/src/insets/insetbibtex.C b/src/insets/insetbibtex.C
index 5c59adf702..d0f8ff7d66 100644
--- a/src/insets/insetbibtex.C
+++ b/src/insets/insetbibtex.C
@@ -44,7 +44,7 @@ using support::ascii_lowercase;
 using support::changeExtension;
 using support::contains;
 using support::copy;
-using support::FileName;
+using support::DocFileName;
 using support::findtexfile;
 using support::isFileReadable;
 using support::latex_path;
@@ -175,7 +175,7 @@ int InsetBibtex::latex(Buffer const & buffer, odocstream & os,
 		    isFileReadable(in_file)) {
 
 			// mangledFilename() needs the extension
-			database = removeExtension(FileName(in_file).mangledFilename());
+			database = removeExtension(DocFileName(in_file).mangledFilename());
 			string const out_file = makeAbsPath(database + ".bib",
 					buffer.getMasterBuffer()->temppath());
 
@@ -231,7 +231,7 @@ int InsetBibtex::latex(Buffer const & buffer, odocstream & os,
 		    isFileReadable(in_file)) {
 			// use new style name
 			base = removeExtension(
-					FileName(in_file).mangledFilename());
+					DocFileName(in_file).mangledFilename());
 			string const out_file = makeAbsPath(base + ".bst",
 					buffer.getMasterBuffer()->temppath());
 			bool const success = copy(in_file, out_file);
diff --git a/src/insets/insetexternal.h b/src/insets/insetexternal.h
index 1ae2dcf2de..0ca0a06fd2 100644
--- a/src/insets/insetexternal.h
+++ b/src/insets/insetexternal.h
@@ -79,7 +79,7 @@ public:
 	std::string const & templatename() const { return templatename_; }
 
 	/// The external file.
-	support::FileName filename;
+	support::DocFileName filename;
 	/// How the inset is to be displayed by LyX.
 	external::DisplayType display;
 	/// The scale of the displayed graphic (if shown).
diff --git a/src/insets/insetgraphics.C b/src/insets/insetgraphics.C
index 16d12a2094..13e457b702 100644
--- a/src/insets/insetgraphics.C
+++ b/src/insets/insetgraphics.C
@@ -95,7 +95,7 @@ using support::bformat;
 using support::changeExtension;
 using support::compare_timestamps;
 using support::contains;
-using support::FileName;
+using support::DocFileName;
 using support::float_equal;
 using support::getExtension;
 using support::isFileReadable;
@@ -483,7 +483,7 @@ copyFileIfNeeded(string const & file_in, string const & file_out)
 
 
 std::pair<CopyStatus, string> const
-copyToDirIfNeeded(FileName const & file, string const & dir)
+copyToDirIfNeeded(DocFileName const & file, string const & dir)
 {
 	using support::rtrim;
 
diff --git a/src/insets/insetgraphicsParams.h b/src/insets/insetgraphicsParams.h
index f8ee53d462..8b2a628424 100644
--- a/src/insets/insetgraphicsParams.h
+++ b/src/insets/insetgraphicsParams.h
@@ -30,7 +30,7 @@ class InsetGraphicsParams
 {
 public:
 	/// Image filename.
-	support::FileName filename;
+	support::DocFileName filename;
 	/// Scaling the Screen inside Lyx
 	unsigned int lyxscale;
 	/// How to display the image inside LyX
diff --git a/src/insets/insetinclude.C b/src/insets/insetinclude.C
index aa57fb7831..f0954516f4 100644
--- a/src/insets/insetinclude.C
+++ b/src/insets/insetinclude.C
@@ -59,7 +59,7 @@ using support::bformat;
 using support::changeExtension;
 using support::contains;
 using support::copy;
-using support::FileName;
+using support::DocFileName;
 using support::getFileContents;
 using support::isFileReadable;
 using support::isLyXFilename;
@@ -390,7 +390,7 @@ int InsetInclude::latex(Buffer const & buffer, odocstream & os,
 
 	// write it to a file (so far the complete file)
 	string const exportfile = changeExtension(incfile, ".tex");
-	string const mangled = FileName(changeExtension(included_file,
+	string const mangled = DocFileName(changeExtension(included_file,
 							".tex")).mangledFilename();
 	string const writefile = makeAbsPath(mangled, m_buffer->temppath());
 
@@ -524,7 +524,7 @@ int InsetInclude::docbook(Buffer const & buffer, odocstream & os,
 	if (loadIfNeeded(buffer, params_)) {
 		Buffer * tmp = theBufferList().getBuffer(included_file);
 
-		string const mangled = FileName(writefile).mangledFilename();
+		string const mangled = DocFileName(writefile).mangledFilename();
 		writefile = makeAbsPath(mangled,
 					buffer.getMasterBuffer()->temppath());
 		if (!runparams.nice)
@@ -568,7 +568,7 @@ void InsetInclude::validate(LaTeXFeatures & features) const
 		writefile = included_file;
 
 	if (!features.runparams().nice && !isVerbatim(params_)) {
-		incfile = FileName(writefile).mangledFilename();
+		incfile = DocFileName(writefile).mangledFilename();
 		writefile = makeAbsPath(incfile,
 					buffer.getMasterBuffer()->temppath());
 	}
diff --git a/src/support/filename.C b/src/support/filename.C
index 609c93b258..63c15df3fe 100644
--- a/src/support/filename.C
+++ b/src/support/filename.C
@@ -31,18 +31,39 @@ namespace support {
 
 
 FileName::FileName()
-	: save_abs_path_(true)
 {}
 
 
-FileName::FileName(string const & abs_filename, bool save_abs)
-	: name_(abs_filename), save_abs_path_(save_abs), zipped_valid_(false)
+FileName::FileName(string const & abs_filename)
+	: name_(abs_filename)
 {
 	BOOST_ASSERT(absolutePath(name_));
 }
 
 
-void FileName::set(string const & name, string const & buffer_path)
+bool operator==(FileName const & lhs, FileName const & rhs)
+{
+	return lhs.absFilename() == rhs.absFilename();
+}
+
+
+bool operator!=(FileName const & lhs, FileName const & rhs)
+{
+	return lhs.absFilename() != rhs.absFilename();
+}
+
+
+DocFileName::DocFileName()
+	: save_abs_path_(true)
+{}
+
+
+DocFileName::DocFileName(string const & abs_filename, bool save_abs)
+	: FileName(abs_filename), save_abs_path_(save_abs), zipped_valid_(false)
+{}
+
+
+void DocFileName::set(string const & name, string const & buffer_path)
 {
 	save_abs_path_ = absolutePath(name);
 	name_ = save_abs_path_ ? name : makeAbsPath(name, buffer_path);
@@ -50,28 +71,28 @@ void FileName::set(string const & name, string const & buffer_path)
 }
 
 
-void FileName::erase()
+void DocFileName::erase()
 {
 	name_.erase();
 	zipped_valid_ = false;
 }
 
 
-string const FileName::relFilename(string const & path) const
+string const DocFileName::relFilename(string const & path) const
 {
 	return makeRelPath(name_, path);
 }
 
 
-string const FileName::outputFilename(string const & path) const
+string const DocFileName::outputFilename(string const & path) const
 {
 	return save_abs_path_ ? name_ : makeRelPath(name_, path);
 }
 
 
-string const FileName::mangledFilename(std::string const & dir) const
+string const DocFileName::mangledFilename(std::string const & dir) const
 {
-	// We need to make sure that every FileName instance for a given
+	// We need to make sure that every DocFileName instance for a given
 	// filename returns the same mangled name.
 	typedef map<string, string> MangledMap;
 	static MangledMap mangledNames;
@@ -125,7 +146,7 @@ string const FileName::mangledFilename(std::string const & dir) const
 }
 
 
-bool FileName::isZipped() const
+bool DocFileName::isZipped() const
 {
 	if (!zipped_valid_) {
 		zipped_ = zippedFile(name_);
@@ -135,20 +156,20 @@ bool FileName::isZipped() const
 }
 
 
-string const FileName::unzippedFilename() const
+string const DocFileName::unzippedFilename() const
 {
 	return unzippedFileName(name_);
 }
 
 
-bool operator==(FileName const & lhs, FileName const & rhs)
+bool operator==(DocFileName const & lhs, DocFileName const & rhs)
 {
 	return lhs.absFilename() == rhs.absFilename() &&
 		lhs.saveAbsPath() == rhs.saveAbsPath();
 }
 
 
-bool operator!=(FileName const & lhs, FileName const & rhs)
+bool operator!=(DocFileName const & lhs, DocFileName const & rhs)
 {
 	return !(lhs == rhs);
 }
diff --git a/src/support/filename.h b/src/support/filename.h
index 285f86efca..0d468bd66b 100644
--- a/src/support/filename.h
+++ b/src/support/filename.h
@@ -19,13 +19,49 @@ namespace lyx {
 namespace support {
 
 
+/**
+ * Class for storing file names.
+ * The file name may be empty. If it is not empty it is an absolute path.
+ * The file may or may not exist.
+ */
 class FileName {
-public:
+protected:
+	/// Constructor for empty filenames (only needed for DocFileName)
 	FileName();
+public:
+	/** Constructor for nonempty filenames.
+	 * \param abs_filename the file in question. Must have an absolute path.
+	 */
+	FileName(std::string const & abs_filename);
+	/// Is this filename empty?
+	bool empty() const { return name_.empty(); }
+	/// get the absolute file name
+	std::string const absFilename() const { return name_; }
+protected:
+	/// The absolute file name.
+	/// The encoding is currently unspecified, anything else than ASCII
+	/// may or may not work.
+	std::string name_;
+};
+
+
+bool operator==(FileName const &, FileName const &);
+bool operator!=(FileName const &, FileName const &);
+
+
+/**
+ * Class for storing file names that appear in documents (e. g. child
+ * documents, included figures etc).
+ * The file name must not denote a file in our temporary directory, but a
+ * file that the user chose.
+ */
+class DocFileName : public FileName {
+public:
+	DocFileName();
 	/** \param abs_filename the file in question. Must have an absolute path.
 	 *  \param save_abs_path how is the file to be output to file?
 	 */
-	FileName(std::string const & abs_filename, bool save_abs_path = true);
+	DocFileName(std::string const & abs_filename, bool save_abs_path = true);
 
 	/** \param filename the file in question. May have either a relative
 	 *  or an absolute path.
@@ -35,10 +71,8 @@ public:
 	void set(std::string const & filename, std::string const & buffer_path);
 
 	void erase();
-	bool empty() const { return name_.empty(); }
 
 	bool saveAbsPath() const { return save_abs_path_; }
-	std::string const absFilename() const { return name_; }
 	/// \param buffer_path if empty, uses `pwd`
 	std::string const relFilename(std::string const & buffer_path = std::string()) const;
 	/// \param buf_path if empty, uses `pwd`
@@ -73,7 +107,6 @@ public:
 	std::string const unzippedFilename() const;
 
 private:
-	std::string name_;
 	bool save_abs_path_;
 	/// Cache for isZipped() because zippedFile() is expensive
 	mutable bool zipped_;
@@ -82,8 +115,8 @@ private:
 };
 
 
-bool operator==(FileName const &, FileName const &);
-bool operator!=(FileName const &, FileName const &);
+bool operator==(DocFileName const &, DocFileName const &);
+bool operator!=(DocFileName const &, DocFileName const &);
 
 
 } // namespace support