diff --git a/virt-back b/virt-back
index 3aa71b4..2487f21 100755
--- a/virt-back
+++ b/virt-back
@@ -124,7 +124,9 @@ def backup(doms):
             f.write(xml)
 
         # Updated regular expression to match file= and dev= within <disk> elements
-        disklist = re.findall(r"<disk.*?<source (?:file|dev)='(.*?)'.*?</disk>", xml, re.DOTALL)
+        disklist = re.findall(
+            r"<disk.*?<source (?:file|dev)='(.*?)'.*?</disk>", xml, re.DOTALL
+        )
 
         logit("backup", "invoking backup for " + dom.name())
 
@@ -137,13 +139,24 @@ def backup(doms):
 
             if is_zfs_dataset(disk_source):
                 # Handle ZFS dataset
-                zfs_dataset = disk_source[len('/dev/zvol/'):] if disk_source.startswith('/dev/zvol/') else disk_source
+                zfs_dataset = (
+                    disk_source[len("/dev/zvol/") :]
+                    if disk_source.startswith("/dev/zvol/")
+                    else disk_source
+                )
                 zfs_snapshot_base = f"{zfs_dataset}@backup-{TODAY}"
                 zfs_snapshot = zfs_snapshot_base
                 suffix = 1
 
                 # Increment snapshot name until an available name is found
-                while subprocess.run(["zfs", "list", zfs_snapshot], stdout=subprocess.PIPE, stderr=subprocess.PIPE).returncode == 0:
+                while (
+                    subprocess.run(
+                        ["zfs", "list", zfs_snapshot],
+                        stdout=subprocess.PIPE,
+                        stderr=subprocess.PIPE,
+                    ).returncode
+                    == 0
+                ):
                     zfs_snapshot = f"{zfs_snapshot_base}-{suffix}"
                     suffix += 1
 
@@ -152,7 +165,9 @@ def backup(doms):
                     zfs_file += ".gz"
 
                 # Create ZFS snapshot
-                logit("backup", f"creating ZFS snapshot {zfs_snapshot} for {dom.name()}")
+                logit(
+                    "backup", f"creating ZFS snapshot {zfs_snapshot} for {dom.name()}"
+                )
                 try:
                     subprocess.run(["zfs", "snapshot", zfs_snapshot], check=True)
                 except subprocess.CalledProcessError as e:
@@ -160,14 +175,23 @@ def backup(doms):
                     continue
 
                 # Send ZFS snapshot to file with optional compression
-                logit("backup", f"sending ZFS snapshot {zfs_snapshot} to {zfs_file} for {dom.name()}")
+                logit(
+                    "backup",
+                    f"sending ZFS snapshot {zfs_snapshot} to {zfs_file} for {dom.name()}",
+                )
                 try:
                     with open(zfs_file, "wb") as f:
                         if options.nogzip:
-                            subprocess.run(["zfs", "send", zfs_snapshot], stdout=f, check=True)
+                            subprocess.run(
+                                ["zfs", "send", zfs_snapshot], stdout=f, check=True
+                            )
                         else:
-                            send_proc = subprocess.Popen(["zfs", "send", zfs_snapshot], stdout=subprocess.PIPE)
-                            gzip_proc = subprocess.Popen(["gzip"], stdin=send_proc.stdout, stdout=f)
+                            send_proc = subprocess.Popen(
+                                ["zfs", "send", zfs_snapshot], stdout=subprocess.PIPE
+                            )
+                            gzip_proc = subprocess.Popen(
+                                ["gzip"], stdin=send_proc.stdout, stdout=f
+                            )
                             send_proc.stdout.close()  # Allow send_proc to receive a SIGPIPE if gzip_proc exits
                             gzip_proc.communicate()
                 except subprocess.CalledProcessError as e:
@@ -222,7 +246,10 @@ def backup(doms):
                     tar.add(zfs_file)  # add zfs snapshot to tar
                     remove(zfs_file)  # cleanup tmp files
                 else:
-                    logit("error", f"ZFS snapshot file {zfs_file} not found for {dom.name()}")
+                    logit(
+                        "error",
+                        f"ZFS snapshot file {zfs_file} not found for {dom.name()}",
+                    )
             else:
                 disk_file = disk_source.split("/")[-1]
                 disk_dest = path.join(options.backpath, disk_file)
@@ -240,12 +267,14 @@ def is_zfs_dataset(disk_source):
     logit("backup", f"checking if {disk_source} is a ZFS dataset")
     try:
         # Extract the ZFS dataset name from the device path
-        if disk_source.startswith('/dev/zvol/'):
-            zfs_dataset = disk_source[len('/dev/zvol/'):]
+        if disk_source.startswith("/dev/zvol/"):
+            zfs_dataset = disk_source[len("/dev/zvol/") :]
         else:
             zfs_dataset = disk_source
 
-        result = subprocess.run(["zfs", "list", zfs_dataset], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        result = subprocess.run(
+            ["zfs", "list", zfs_dataset], stdout=subprocess.PIPE, stderr=subprocess.PIPE
+        )
         is_zfs = result.returncode == 0
         logit("backup", f"{zfs_dataset} is {'a' if is_zfs else 'not a'} ZFS dataset")
         return is_zfs