diff --git a/src/formatting/DefaultTagFormatter.ts b/src/formatting/DefaultTagFormatter.ts
index 0ce0393..5b8d295 100644
--- a/src/formatting/DefaultTagFormatter.ts
+++ b/src/formatting/DefaultTagFormatter.ts
@@ -63,10 +63,10 @@ export class DefaultTagFormatter implements TagFormatter {
 
   public IsValid(tag: string): boolean {        
     if (!!this.namespace) {
-      return new RegExp(`^${this.tagPrefix}[0-9]+.[0-9]+.[0-9]+${this.namespaceSeperator}${this.namespace}$`).test(tag);
+      return new RegExp(`^${this.tagPrefix}[0-9]+\.[0-9]+\.[0-9]+${this.namespaceSeperator}${this.namespace}$`).test(tag);
     }
 
-    return new RegExp(`^${this.tagPrefix}[0-9]+.[0-9]+.[0-9]+$`).test(tag);
+    return new RegExp(`^${this.tagPrefix}[0-9]+\.[0-9]+\.[0-9]+$`).test(tag);
   }
 
 }