diff --git a/Join-Object.ps1 b/Join-Object.ps1
index 6549c792..4bf2ce30 100644
--- a/Join-Object.ps1
+++ b/Join-Object.ps1
@@ -200,10 +200,12 @@
     (
         [Parameter(Mandatory=$true,
                    ValueFromPipeLine = $true)]
+        [AllowEmptyCollection()]
         [object[]] $Left,
 
         # List to join with $Left
         [Parameter(Mandatory=$true)]
+        [AllowEmptyCollection()]
         [object[]] $Right,
 
         [Parameter(Mandatory = $true)]
@@ -493,4 +495,4 @@
             }
         }
     }
-}
\ No newline at end of file
+}