https://github.com/fifengine/fifengine/issues/1085

Index: engine/core/gui/fifechan/fifechanmanager.cpp
--- engine/core/gui/fifechan/fifechanmanager.cpp.orig
+++ engine/core/gui/fifechan/fifechanmanager.cpp
@@ -249,7 +249,9 @@ namespace FIFE {
 
 		IFont* font = NULL;
 		GuiFont* guifont = NULL;
-		if( bfs::extension(fontpath) == ".ttf" || bfs::extension(fontpath) == ".ttc" ) {
+		bfs::path p = fontpath;
+		std::string s = p.extension().string();
+		if( s == ".ttf" || s == ".ttc" ) {
 			font = new TrueTypeFont(fontpath, fontsize);
 		} else {
 			font = new SubImageFont(fontpath, fontglyphs);
