[LyX/master] Fix regression of 2fc430d5ae

[Georg Baum]

commit 1d3a85fe37737b9f8de06f2e0299330908cb916d
Author: Georg Baum <b...@lyx.org>
Date:   Mon Nov 9 20:06:36 2015 +0100

    Fix regression of 2fc430d5ae
    
    Thanks Kornel for noticing

diff --git a/src/BufferParams.cpp b/src/BufferParams.cpp
index a73194d..6ecc68a 100644
--- a/src/BufferParams.cpp
+++ b/src/BufferParams.cpp
@@ -1106,7 +1106,7 @@ void BufferParams::writeFile(ostream & os, Buffer const * 
buf) const
           << "\" \"" << fonts_sans[1] << '"'
           << "\n\\font_typewriter \"" << fonts_typewriter[0]
           << "\" \"" << fonts_typewriter[1] << '"'
-          << "\n\\font_math " << fonts_math[0]
+          << "\n\\font_math \"" << fonts_math[0]
           << "\" \"" << fonts_math[1] << '"'
           << "\n\\font_default_family " << fonts_default_family
           << "\n\\use_non_tex_fonts " << convert<string>(useNonTeXFonts)