diff --git a/tests/test_nginx_vhosts.py b/tests/test_nginx_vhosts.py
index 158386c1036b92559747c540bf2ed2013524f873..ea0cd1a15e3fde50680365c225c89c37e69add35 100755
--- a/tests/test_nginx_vhosts.py
+++ b/tests/test_nginx_vhosts.py
@@ -91,11 +91,11 @@ def test_vhost(
     name = nginx_file.name
     for port, proto in ports_info or [(80, False)]:
         for domain in domains or ["localhost"]:
-            url = "%s://%s:%s" % (proto, domain, port)
-            u.info("- testing url '%s' from %s" % (url, name))
+            url = f"{proto}://{domain}:{port}"
+            u.info(f"- testing url '{url}' from {name}")
             if name.startswith("mediaserver") and not tested:
                 if not re.search(r"https?://%s" % domain, celerity_conf):
-                    u.warning("url '%s' not found in celerity conf" % url)
+                    u.warning(f"url '{url}' not found in celerity conf")
                     warnings += 1
             # test domain IP
             ip_error = None
@@ -103,19 +103,19 @@ def test_vhost(
             try:
                 ip = socket.gethostbyname(domain)
             except Exception as e:
-                ip_error = "domain: not resolved %s" % e
+                ip_error = f"domain: not resolved {e}"
             else:
                 if ip != "127.0.0.1":
-                    ip_warning = "domain: resolve to %s instead of 127.0.0.1" % ip
+                    ip_warning = f"domain: resolve to {ip} instead of 127.0.0.1"
             if ip_error:
                 if resolution_ignored and domain in resolution_ignored:
-                    u.info("%s (ignored)" % ip_error)
+                    u.info(f"{ip_error} (ignored)")
                     ip_error = None
                 else:
                     u.error(ip_error)
             elif ip_warning:
                 if resolution_ignored and domain in resolution_ignored:
-                    u.info("%s (ignored)" % ip_warning)
+                    u.info(f"{ip_warning} (ignored)")
                     ip_warning = None
                 else:
                     u.warning(ip_warning)
@@ -139,14 +139,14 @@ def test_vhost(
                 or domain == "localhost"
                 and code not in (200, 401, 403, 404)
             ):
-                u.error("status: %s, %sms" % (code, req_time))
+                u.error(f"status: {code}, {req_time}ms")
                 req_error = True
             else:
                 if req_time > 10000:
-                    u.warning("status: %s, %sms" % (code, req_time))
+                    u.warning(f"status: {code}, {req_time}ms")
                     warnings += 1
                 else:
-                    u.success("status: %s, %sms" % (code, req_time))
+                    u.success(f"status: {code}, {req_time}ms")
                 if "mediaserver" in name and wowza_dir:
                     # test /streaming url
                     try:
@@ -163,13 +163,13 @@ def test_vhost(
                     else:
                         code = req.status_code
                     if code != 200:
-                        u.error("streaming: %s, %sms" % (code, req_time))
+                        u.error(f"streaming: {code}, {req_time}ms")
                         req_error = True
                     elif req_time > 10000:
-                        u.warning("streaming: %s, %sms" % (code, req_time))
+                        u.warning(f"streaming: {code}, {req_time}ms")
                         warnings += 1
                     else:
-                        u.success("streaming: %s, %sms" % (code, req_time))
+                        u.success(f"streaming: {code}, {req_time}ms")
             tested += 1
 
             if ip_warning:
@@ -185,13 +185,13 @@ def main():
     # check that Nginx dir exists
     nginx_dir = "/etc/nginx/sites-enabled"
     if not Path(nginx_dir).exists():
-        u.info("nginx dir does not exists ('%s'), test skipped." % nginx_dir)
+        u.info(f"nginx dir does not exists ('{nginx_dir}'), test skipped.")
         exit(2)
 
     # check that Wowza is installed
     wowza_dir = "/usr/local/WowzaStreamingEngine"
     if not Path(wowza_dir).exists():
-        u.info("wowza is not installed ('%s' does not exist)." % wowza_dir)
+        u.info(f"wowza is not installed ('wowza_dir' does not exist).")
         wowza_dir = None
     else:
         u.info("wowza is installed, /streaming/ will be tested on mediaserver vhosts.")