diff --git a/src/Models/TemplateEngine.cs b/src/Models/TemplateEngine.cs
index 6b5f525df..8472750c1 100644
--- a/src/Models/TemplateEngine.cs
+++ b/src/Models/TemplateEngine.cs
@@ -313,7 +313,7 @@ private string ParseReplacement()
 
         private static bool IsNameChar(char c)
         {
-            return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9');
+            return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_';
         }
 
         // (?) notice or log if variable is not found