diff --git a/Commands/Public/New-CosmosDocuument.ps1 b/Commands/Public/New-CosmosDocuument.ps1
index 0eeee32..4fe9f82 100644
--- a/Commands/Public/New-CosmosDocuument.ps1
+++ b/Commands/Public/New-CosmosDocuument.ps1
@@ -91,6 +91,8 @@ function New-CosmosDocument
         if($PSCmdlet.ParameterSetName -eq 'DocumentObject')
         {
             $Document = $DocumentObject | ConvertTo-Json -Depth 99 -Compress
+            #when in pipeline in PS5.1, parameter retains value across invocations
+            $PartitionKey = @()
             foreach($attribute in $PartitionKeyAttribute)
             {
                 $PartitionKey+=$DocumentObject."$attribute"
diff --git a/Commands/Public/Set-CosmosDocument.ps1 b/Commands/Public/Set-CosmosDocument.ps1
index d3bc999..261b737 100644
--- a/Commands/Public/Set-CosmosDocument.ps1
+++ b/Commands/Public/Set-CosmosDocument.ps1
@@ -88,6 +88,9 @@ function Set-CosmosDocument
         {
             #to change document Id, you cannot use DocumentObject parameter set
             $Id = $DocumentObject.id
+            #when in pipeline in PS5.1, parameter retains value across invocations
+            $PartitionKey = @()
+
             foreach($attribute in $PartitionKeyAttribute)
             {
                 $PartitionKey+=$DocumentObject."$attribute"