diff --git a/examples/protocols/https_x509_bundle/pytest_https_x509_bundle.py b/examples/protocols/https_x509_bundle/pytest_https_x509_bundle.py
index 8b4b89ca8f1..8d3e8fc5384 100644
--- a/examples/protocols/https_x509_bundle/pytest_https_x509_bundle.py
+++ b/examples/protocols/https_x509_bundle/pytest_https_x509_bundle.py
@@ -20,13 +20,13 @@ def test_examples_protocol_https_x509_bundle(dut: Dut) -> None:
     # check and log bin size
     binary_file = os.path.join(dut.app.binary_path, 'https_x509_bundle.bin')
     bin_size = os.path.getsize(binary_file)
-    logging.info('https_x509_bundle_bin_size : {}KB'.format(bin_size // 1024))
+    logging.info(f'https_x509_bundle_bin_size : {bin_size // 1024}KB')
     dut.expect(r'IPv4 address: (\d+\.\d+\.\d+\.\d+)[^\d]', timeout=30)
     # start test
     num_URLS = int(dut.expect(r'Connecting to (\d+) URLs', timeout=30)[1].decode())
     for _ in range(num_URLS):
         dut.expect(r'Connection established to ([\s\S]*)', timeout=30)
-    dut.expect('Completed {} connections'.format(num_URLS), timeout=60)
+    dut.expect(f'Completed {num_URLS} connections', timeout=60)
 
 
 @pytest.mark.ethernet
@@ -43,12 +43,12 @@ def test_examples_protocol_https_x509_bundle_dynamic_buffer(dut: Dut) -> None:
     # check and log bin size
     binary_file = os.path.join(dut.app.binary_path, 'https_x509_bundle.bin')
     bin_size = os.path.getsize(binary_file)
-    logging.info('https_x509_bundle_bin_size : {}KB'.format(bin_size // 1024))
+    logging.info(f'https_x509_bundle_bin_size : {bin_size // 1024}KB')
     dut.expect(r'IPv4 address: (\d+\.\d+\.\d+\.\d+)[^\d]', timeout=30)
     # start test
     num_URLS = int(dut.expect(r'Connecting to (\d+) URLs', timeout=30)[1].decode())
     dut.expect(r'Connection established to ([\s\S]*)', timeout=30)
-    dut.expect('Completed {} connections'.format(num_URLS), timeout=60)
+    dut.expect(f'Completed {num_URLS} connections', timeout=60)
 
 
 @pytest.mark.qemu
@@ -65,10 +65,10 @@ def test_examples_protocol_https_x509_bundle_default_crt_bundle_stress_test(dut:
     # check and log bin size
     binary_file = os.path.join(dut.app.binary_path, 'https_x509_bundle.bin')
     bin_size = os.path.getsize(binary_file)
-    logging.info('https_x509_bundle_bin_size : {}KB'.format(bin_size // 1024))
+    logging.info(f'https_x509_bundle_bin_size : {bin_size // 1024}KB')
     dut.expect(r'IPv4 address: (\d+\.\d+\.\d+\.\d+)[^\d]', timeout=30)
     # start test
     num_URLS = int(dut.expect(r'Connecting to (\d+) URLs', timeout=30)[1].decode())
     for _ in range(num_URLS):
         dut.expect(r'Connection established to ([\s\S]*)', timeout=60)
-    dut.expect('Completed {} connections'.format(num_URLS), timeout=180)
+    dut.expect(f'Completed {num_URLS} connections', timeout=180)