diff --git a/microsoft/testsuites/cloud_hypervisor/ch_tests.py b/microsoft/testsuites/cloud_hypervisor/ch_tests.py
index d0656403e3..307e023329 100644
--- a/microsoft/testsuites/cloud_hypervisor/ch_tests.py
+++ b/microsoft/testsuites/cloud_hypervisor/ch_tests.py
@@ -202,7 +202,8 @@ def _set_ms_clh_param(self, variables: Dict[str, Any]) -> None:
         CloudHypervisorTests.ms_clh_repo = ms_clh_repo
         CloudHypervisorTests.ms_igvm_parser_repo = ms_igvm_parser_repo
         CloudHypervisorTests.clh_guest_vm_type = clh_guest_vm_type
-        CloudHypervisorTests.use_ms_guest_kernel = use_ms_guest_kernel
+        if use_ms_guest_kernel == "YES":
+            CloudHypervisorTests.use_ms_guest_kernel = use_ms_guest_kernel
 
 
 def get_test_list(variables: Dict[str, Any], var1: str, var2: str) -> Any:
diff --git a/microsoft/testsuites/cloud_hypervisor/ch_tests_tool.py b/microsoft/testsuites/cloud_hypervisor/ch_tests_tool.py
index 64395bf3dc..3f1124912f 100644
--- a/microsoft/testsuites/cloud_hypervisor/ch_tests_tool.py
+++ b/microsoft/testsuites/cloud_hypervisor/ch_tests_tool.py
@@ -230,7 +230,8 @@ def _install(self) -> bool:
                 auth_token=self.ms_access_token,
             )
             self.env_vars["GUEST_VM_TYPE"] = self.clh_guest_vm_type
-            self.env_vars["USE_MS_GUEST_KERNEL"] = self.use_ms_guest_kernel
+            if self.use_ms_guest_kernel:
+                self.env_vars["USE_MS_GUEST_KERNEL"] = self.use_ms_guest_kernel
         else:
             git.clone(self.upstream_repo, clone_path)