diff --git a/TrimSPlib.js b/TrimSPlib.js
index c46fff0..0950b33 100644
--- a/TrimSPlib.js
+++ b/TrimSPlib.js
@@ -141,7 +141,7 @@ function Zof(Element)
 function Massof(Element)
 {
     var ElementsA = {
-	"Muon":0.113,
+	"Muon":0.1134289259,
 	"Li8":8.0,
 	"B12":12.0,
 	"H":1.00800,