diff --git a/tiny_obj_loader.h b/tiny_obj_loader.h
index 02ef7b0..dd8f061 100644
--- a/tiny_obj_loader.h
+++ b/tiny_obj_loader.h
@@ -803,7 +803,7 @@ void LoadMtl(std::map<std::string, int> &material_map,
 
     // transmittance
     if ((token[0] == 'K' && token[1] == 't' && IS_SPACE((token[2])))
-        || (token[0] == 'T' && token[1] == 'F' && IS_SPACE((token[2])))) {
+        || (token[0] == 'T' && token[1] == 'f' && IS_SPACE((token[2])))) {
       token += 2;
       float r, g, b;
       parseFloat3(r, g, b, token);