diff --git a/Orleans.Providers.MongoDB/Membership/Store/Single/SingleMembershipCollection.cs b/Orleans.Providers.MongoDB/Membership/Store/Single/SingleMembershipCollection.cs
index 986d96f..e3f7240 100644
--- a/Orleans.Providers.MongoDB/Membership/Store/Single/SingleMembershipCollection.cs
+++ b/Orleans.Providers.MongoDB/Membership/Store/Single/SingleMembershipCollection.cs
@@ -92,8 +92,11 @@ public async Task<MembershipTableData> ReadRow(string deploymentId, SiloAddress
 
         public async Task UpdateIAmAlive(string deploymentId, SiloAddress address, DateTime iAmAliveTime)
         {
-            await Collection.UpdateOneAsync(x => x.DeploymentId == deploymentId,
-                Update
+            var filter = Builders<DeploymentDocument>.Filter.And(
+                Builders<DeploymentDocument>.Filter.Eq(x => x.DeploymentId, deploymentId),
+                Builders<DeploymentDocument>.Filter.Exists($"Members.{BuildKey(address)}", true));
+
+            await Collection.UpdateOneAsync(filter, Update
                     .Set($"Members.{BuildKey(address)}.IAmAliveTime", LogFormatter.PrintDate(iAmAliveTime)));
         }