diff --git a/src/azure-cli/azure/cli/command_modules/acs/custom.py b/src/azure-cli/azure/cli/command_modules/acs/custom.py
index c59e33d4514..8915bee86fd 100644
--- a/src/azure-cli/azure/cli/command_modules/acs/custom.py
+++ b/src/azure-cli/azure/cli/command_modules/acs/custom.py
@@ -2570,7 +2570,7 @@ def aks_agentpool_upgrade(cmd, client, resource_group_name, cluster_name,
         instance.upgrade_settings.max_surge = max_surge
     if drain_timeout:
         instance.upgrade_settings.drain_timeout_in_minutes = drain_timeout
-    if node_soak_duration:
+    if isinstance(node_soak_duration, int) and node_soak_duration >= 0:
         instance.upgrade_settings.node_soak_duration_in_minutes = node_soak_duration
 
     # custom headers