diff --git a/lib/loadMtl.js b/lib/loadMtl.js
index 6d3f506..5b5c72b 100644
--- a/lib/loadMtl.js
+++ b/lib/loadMtl.js
@@ -66,7 +66,7 @@ function loadMtl(mtlPath) {
             material.alpha = parseFloat(value);
         } else if (/^Tr /i.test(line)) {
             value = line.substring(3).trim();
-            material.alpha = parseFloat(value);
+            material.alpha = 1.0 - parseFloat(value);
         } else if (/^map_Ka /i.test(line)) {
             material.ambientTexture = path.resolve(mtlDirectory, line.substring(7).trim());
         } else if (/^map_Ke /i.test(line)) {