diff --git a/magisk_boot_flasher.py b/magisk_boot_flasher.py
index 344c475..8c5a596 100644
--- a/magisk_boot_flasher.py
+++ b/magisk_boot_flasher.py
@@ -1,3 +1,4 @@
+from pathlib import Path
 import requests
 import hashlib
 import sys
@@ -40,6 +41,15 @@ def yes_or_no(question, default=None):
             print("Please respond with 'yes' or 'no' " "(or 'y' or 'n').\n")
 
 
+def isAdbConnected():
+    cmdlist = ['adb', 'devices']
+    sp = subprocess.run(cmdlist, capture_output=True)
+    if len(sp.stdout.split(b'\n')) < 4:
+        return False
+    else:
+        return True
+
+
 def isMagiskInstalled():
     cmdlist = ['adb', 'shell', 'command', '-v', 'su']
     sp = subprocess.run(cmdlist, stdout=subprocess.DEVNULL,
@@ -59,14 +69,20 @@ def checkInstalledVersion():
 
 def downloadUpdate(device, version):
     filename = f"lineage-{version}.zip"
-    url = f'https://download.lineage.microg.org/{device}/{filename}'
-    r = requests.get(url, stream=True)
-    with tqdm.wrapattr(open(filename, "wb"), "write",
-                       miniters=1, desc=filename,
-                       total=int(r.headers.get('Content-Length'))) as fout:
-        for chunk in r.iter_content(chunk_size=4096):
-            fout.write(chunk)
-    fout.close()
+
+    if Path(filename).exists():
+        print(f'{filename} already found locally.')
+    else:
+        url = f'https://download.lineage.microg.org/{device}/{filename}'
+        r = requests.get(url, stream=True)
+        with tqdm.wrapattr(open(filename, "wb"),
+                           "write",
+                           miniters=1,
+                           desc=filename,
+                           total=int(r.headers.get('Content-Length'))) as fout:
+            for chunk in r.iter_content(chunk_size=4096):
+                fout.write(chunk)
+        fout.close()
 
     print('Comparing hashes...', end='', flush=True)
     checkHash(filename)
@@ -150,6 +166,13 @@ def cleanUp(filename):
 
 
 if __name__ == "__main__":
+    print("Checking if an adb device is connected...", end='', flush=True)
+    if not isAdbConnected():
+        print("\nNo adb device is connected.")
+        print("Aborting.")
+        sys.exit()
+    print('  [OK]')
+
     print("Checking if Magisk already installed...", end='', flush=True)
     if isMagiskInstalled():
         print("\nIt seems Magisk is already installed (su in PATH).")