diff --git a/app/args.py b/app/args.py
index 19db240..120dfb1 100644
--- a/app/args.py
+++ b/app/args.py
@@ -1,4 +1,4 @@
-#!/usr/local/bin/python3
+#!/usr/local/env python3
 
 import argparse
 
diff --git a/app/ip_info.py b/app/ip_info.py
index 589d28b..9a349ce 100644
--- a/app/ip_info.py
+++ b/app/ip_info.py
@@ -6,7 +6,7 @@ import requests
 
 def get_ip_information(ipv4_address: ipaddress.IPv4Address) -> dict:
     """Retrieves information about a given IPv4 address from IP-API.com."""
-    api_endpoint = "http://ip-api.com/json/{}".format(ipv4_address)
+    api_endpoint = f"http://ip-api.com/json/{ipv4_address}"
     resp = requests.get(api_endpoint).json()
     return resp
 
@@ -19,9 +19,7 @@ def get_autonomous_system_number(as_info: str) -> str:
 
 def get_prefix_information(autonomous_system: int) -> list:
     """Retrieves prefix information about a given autonomous system."""
-    api_endpoint = "https://api.hackertarget.com/aslookup/?q={}".format(
-        str(autonomous_system)
-    )
+    api_endpoint = f"https://api.hackertarget.com/aslookup/?q={str(autonomous_system)}"
     resp = requests.get(api_endpoint).text
     prefixes = resp.split("\n")
     prefixes.pop(0)
diff --git a/app/main.py b/app/main.py
index ed65454..1acf2de 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,9 +1,11 @@
 #!/usr/local/bin/python3
 
+import sys
+
 from app.args import parse_args
 from app.print_table import print_table, generate_prefix_string
 from app.query_normalisation import is_ip_address, resolve_domain_name
-from app.ip_info import (
+from app.ip_info import (  # pragma: no cover
     get_ip_information,
     get_autonomous_system_number,
     get_prefix_information,
@@ -23,17 +25,17 @@ def main():
         print(HEADER)
 
     # Set IP to passed IP address, or resolve passed domain name to IPv4
-    ip = (
+    ip_address = (
         resolve_domain_name(args.query) if not is_ip_address(args.query) else args.query
     )
 
     # If not given an IPv4, and can't resolve to IPv4, then throw error and exit
-    if not ip:
+    if not ip_address:
         print("ERROR: could not resolve query to IPv4 address.")
-        exit(1)
+        sys.exit(1)
 
     # Get information from API
-    ip_info = get_ip_information(ip)
+    ip_info = get_ip_information(ip_address)
     as_number = get_autonomous_system_number(ip_info.get("as"))
 
     # Assemble list for table generation
@@ -42,9 +44,7 @@ def main():
         ["Organization", ip_info.get("org")],
         [
             "Location",
-            "{}/{}/{}".format(
-                ip_info.get("country"), ip_info.get("regionName"), ip_info.get("city")
-            ),
+            f"{ip_info.get('country')}/{ip_info.get('regionName')}/{ip_info.get('city')}",
         ],
         ["Timezone", ip_info.get("timezone")],
         ["Internet Service Provider", ip_info.get("isp")],
diff --git a/app/print_table.py b/app/print_table.py
index 96fcdac..a5813b6 100644
--- a/app/print_table.py
+++ b/app/print_table.py
@@ -4,12 +4,12 @@ from tabulate import tabulate
 
 
 def generate_prefix_string(prefixes: list) -> str:
-    """Generate a string that spilts prefixes into rows of 5."""
-    n = 4
+    """Generate a string that spilts prefixes into rows of 4."""
+    num_per_row = 4
     try:
         ret = ""
-        for i in range(0, len(prefixes), n):
-            ret += ", ".join(prefixes[i : i + n]) + "\n"
+        for i in range(0, len(prefixes), num_per_row):
+            ret += ", ".join(prefixes[i : i + num_per_row]) + "\n"
         return ret
     except AttributeError:
         return None
diff --git a/app/query_normalisation.py b/app/query_normalisation.py
index 6ae9847..fe0cb31 100644
--- a/app/query_normalisation.py
+++ b/app/query_normalisation.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python3
 
+import socket
 import ipaddress
 import requests
-import socket
 
 
 def is_ip_address(query: str) -> bool:
@@ -17,13 +17,13 @@ def is_ip_address(query: str) -> bool:
 def resolve_domain_name(domain_name: str) -> ipaddress.IPv4Address:
     """Resolve a domain name via DNS or return None."""
     try:
-        ip = socket.gethostbyname(domain_name)
+        ip_address = socket.gethostbyname(domain_name)
     except socket.gaierror:
-        ip = None
-    return ip
+        ip_address = None
+    return ip_address
 
 
 def get_public_ip() -> ipaddress.IPv4Address:
     """Get the user's current public IPv4 address."""
-    ip = requests.get("https://api.ipify.org").text
-    return ip
+    ip_address = requests.get("https://api.ipify.org").text
+    return ip_address
diff --git a/tests/test_ip_info.py b/tests/test_ip_info.py
index a0645d5..5b5d79b 100644
--- a/tests/test_ip_info.py
+++ b/tests/test_ip_info.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-from app.ip_info import (
+from app.ip_info import (  # pragma: no cover
     get_ip_information,
     get_autonomous_system_number,
     get_prefix_information,
diff --git a/tests/test_query_normalisation.py b/tests/test_query_normalisation.py
index 1d1f2c1..4a58abd 100644
--- a/tests/test_query_normalisation.py
+++ b/tests/test_query_normalisation.py
@@ -1,6 +1,10 @@
 #!/usr/bin/env python3
 
-from app.query_normalisation import is_ip_address, resolve_domain_name, get_public_ip
+from app.query_normalisation import (  # pragma: no cover
+    is_ip_address,
+    resolve_domain_name,
+    get_public_ip,
+)
 
 
 def test_is_ip_address_true() -> None: