diff --git a/functions-common b/functions-common
index 48e400d..56fa64a 100644
--- a/functions-common
+++ b/functions-common
@@ -62,6 +62,9 @@
     $xtrace
 }
 
+function isset {
+    [[ -v "$1" ]]
+}
 
 # Control Functions
 # =================