diff --git a/tests/framework/defs.py b/tests/framework/defs.py
index 3d16325f71c..b075ecc0deb 100644
--- a/tests/framework/defs.py
+++ b/tests/framework/defs.py
@@ -48,3 +48,7 @@
 
 # Absolute path to the test results folder
 TEST_RESULTS_DIR = FC_WORKSPACE_DIR / "test_results"
+
+# Name of the file that stores firecracker's PID when launched by jailer with
+#  `--new-pid-ns`.
+FC_PID_FILE_NAME = "firecracker.pid"
diff --git a/tests/framework/microvm.py b/tests/framework/microvm.py
index b76422ca8d7..fdb8f9155b6 100644
--- a/tests/framework/microvm.py
+++ b/tests/framework/microvm.py
@@ -28,7 +28,8 @@
 import host_tools.network as net_tools
 
 import framework.utils as utils
-from framework.defs import MICROVM_KERNEL_RELPATH, MICROVM_FSFILES_RELPATH
+from framework.defs import MICROVM_KERNEL_RELPATH, MICROVM_FSFILES_RELPATH, \
+    FC_PID_FILE_NAME
 from framework.http import Session
 from framework.jailer import JailerContext
 from framework.resources import Actions, Balloon, BootSource, Drive, \
@@ -174,6 +175,15 @@ def kill(self):
             utils.run_cmd(
                 'kill -9 {} || true'.format(self.screen_pid))
 
+        # Check if Firecracker was launched by the jailer in a new pid ns.
+        fc_pid_in_new_ns = self.pid_in_new_ns
+
+        if fc_pid_in_new_ns:
+            # We need to explicitly kill the Firecracker pid, since it's
+            # different from the jailer pid that was previously killed.
+            utils.run_cmd(f'kill -9 {fc_pid_in_new_ns}',
+                          ignore_return_code=True)
+
         if self._memory_monitor and self._memory_monitor.is_alive():
             self._memory_monitor.signal_stop()
             self._memory_monitor.join(timeout=1)
@@ -289,6 +299,22 @@ def memory_monitor(self, monitor):
         """Set the memory monitor."""
         self._memory_monitor = monitor
 
+    @property
+    def pid_in_new_ns(self):
+        """Get the pid of the Firecracker process in the new namespace.
+
+        Returns None if Firecracker was not launched in a new pid ns.
+        """
+        fc_pid = None
+
+        pid_file_path = f"{self.jailer.chroot_path()}/{FC_PID_FILE_NAME}"
+        if os.path.exists(pid_file_path):
+            # Read the PID stored inside the file.
+            with open(pid_file_path) as file:
+                fc_pid = int(file.readline())
+
+        return fc_pid
+
     def flush_metrics(self, metrics_fifo):
         """Flush the microvm metrics.
 
diff --git a/tests/integration_tests/security/test_jail.py b/tests/integration_tests/security/test_jail.py
index ccd3a97c838..05410d80d85 100644
--- a/tests/integration_tests/security/test_jail.py
+++ b/tests/integration_tests/security/test_jail.py
@@ -10,15 +10,13 @@
 
 # These are the permissions that all files/dirs inside the jailer have.
 REG_PERMS = stat.S_IRUSR | stat.S_IWUSR | \
-            stat.S_IXUSR | stat.S_IRGRP | stat.S_IXGRP | \
-            stat.S_IROTH | stat.S_IXOTH
+    stat.S_IXUSR | stat.S_IRGRP | stat.S_IXGRP | \
+    stat.S_IROTH | stat.S_IXOTH
 DIR_STATS = stat.S_IFDIR | stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR
 FILE_STATS = stat.S_IFREG | REG_PERMS
 SOCK_STATS = stat.S_IFSOCK | REG_PERMS
 # These are the stats of the devices created by tha jailer.
 CHAR_STATS = stat.S_IFCHR | stat.S_IRUSR | stat.S_IWUSR
-# Name of the file that stores firecracker's PID.
-PID_FILE_NAME = "firecracker.pid"
 
 
 def check_stats(filepath, stats, uid, gid):
@@ -204,14 +202,8 @@ def test_new_pid_namespace(test_microvm_with_ssh):
     test_microvm.spawn()
 
     # Check that the PID file exists.
-    pid_file_path = "{}/{}".format(test_microvm.jailer.chroot_path(),
-                                   PID_FILE_NAME)
-    assert os.path.exists(pid_file_path)
-
-    # Read the PID stored inside the file.
-    with open(pid_file_path) as file:
-        fc_pid = int(file.readline())
-    file.close()
+    fc_pid = test_microvm.pid_in_new_ns
+    assert fc_pid is not None
 
     # Validate the PID.
     stdout = subprocess.check_output("pidof firecracker", shell=True)
@@ -221,9 +213,9 @@ def test_new_pid_namespace(test_microvm_with_ssh):
     # Firecracker process is a member of.
     nstgid_cmd = "cat /proc/{}/status | grep NStgid".format(fc_pid)
     nstgid_list = subprocess.check_output(
-                    nstgid_cmd,
-                    shell=True
-                ).decode('utf-8').strip().split("\t")[1:]
+        nstgid_cmd,
+        shell=True
+    ).decode('utf-8').strip().split("\t")[1:]
 
     # Check that Firecracker's PID namespace is nested. `NStgid` should
     # report two values and the last one should be 1, because Firecracker