diff --git a/lib/index.js b/lib/index.js
index 871ab1b..4b4d0a2 100755
--- a/lib/index.js
+++ b/lib/index.js
@@ -13,7 +13,7 @@ const internals = {
         '[': ']'
     },
 
-    numberRx: /^(?:[0-9]*\.?[0-9]*){1}$/,
+    numberRx: /^(?:[0-9]*(\.[0-9]*)?){1}$/,
     tokenRx: /^[\w\$\#\.\@\:\{\}]+$/,
 
     symbol: Symbol('formula'),