diff --git a/libs/pbd/filesystem.cc b/libs/pbd/filesystem.cc
index ea45b1da44..3c96f5b001 100644
--- a/libs/pbd/filesystem.cc
+++ b/libs/pbd/filesystem.cc
@@ -162,6 +162,22 @@ basename (const path & p)
 	return base.substr (0, n);
 }
 
+string
+extension (const path & p)
+{
+	string base = Glib::path_get_basename (p.to_string());
+
+	string::size_type n = base.rfind ('.');
+
+	if (n != string::npos)
+	{
+		return base.substr(n);
+	}
+
+	return string();
+
+}
+
 } // namespace sys
 
 } // namespace PBD
diff --git a/libs/pbd/pbd/filesystem.h b/libs/pbd/pbd/filesystem.h
index b5f328acf4..5e94138bd8 100644
--- a/libs/pbd/pbd/filesystem.h
+++ b/libs/pbd/pbd/filesystem.h
@@ -172,6 +172,15 @@ void copy_file(const path & from_path, const path & to_path);
  */ 
 string basename (const path& p);
 
+/**
+ * @return If the filename contains a dot, return a substring of the
+ * filename starting the rightmost dot to the end of the string, otherwise
+ * an empty string.
+ *
+ * @param p a file path.
+ */
+string extension (const path& p);
+
 } // namespace sys
 
 } // namespace PBD