diff --git a/pygeckodriver/__init__.py b/pygeckodriver/__init__.py
index 966bb74..c1528c9 100755
--- a/pygeckodriver/__init__.py
+++ b/pygeckodriver/__init__.py
@@ -9,25 +9,21 @@
 
 _BASE_DIR = os.path.dirname(os.path.abspath(__file__))
 
+
 def _get_filename():
-    path = os.path.join(_BASE_DIR, 'geckodriver_')
+    arch = '64' if platform.machine().endswith('64') else '32'
 
     sys = platform.system()
-    arch = platform.machine()
-    file_extension = None
     if sys == 'Darwin':
-        path += 'macos'
+        file_name = 'geckodriver_macos'
+    elif sys == 'Windows':
+        file_name = 'geckodriver_win{}.exe'.format(arch)
+    elif sys == 'Linux':
+        file_name = 'geckodriver_linux{}'.format(arch)
     else:
-        if sys == 'Windows':
-            path += 'win'
-            file_extension = ".exe"
-        elif sys == 'Linux':
-            path += 'linux'
-        else:
-            raise Exception('OS not supported')
-        path += '64' if arch.endswith('64') else '32'
-        path += file_extension
+        raise Exception('OS {} not supported'.format(sys))
 
+    path = os.path.join(_BASE_DIR, file_name)
     if not os.path.exists(path):
         raise FileNotFoundError('GeckoDriver for {}({}) '
                                 'is not found.'.format(sys, arch))
diff --git a/update.py b/update.py
index 0b3f7a4..8989621 100755
--- a/update.py
+++ b/update.py
@@ -85,7 +85,7 @@ def download_geckodriver(version):
                         or 'win64' in filename:
                     filename += '.exe'
 
-                if '.tar.gz' in asset['name']:
+                if asset['name'].endswith('.tar.gz'):
                     tf = tarfile.open(fileobj=BytesIO(requests.get(url).content))
                     for f in tf.getnames():
                         if 'geckodriver' in f:
@@ -93,7 +93,7 @@ def download_geckodriver(version):
                             os.rename(os.path.join(DOWNLOAD_DIR, f), \
                                     os.path.join(DOWNLOAD_DIR, filename))
                             os.chmod(os.path.join(DOWNLOAD_DIR, filename), 0o755)
-                elif '.gz' in asset['name']:
+                elif asset['name'].endswith('.gz'):
                     gf = gzip.GzipFile(fileobj=BytesIO(requests.get(url).content))
                     with open(os.path.join(DOWNLOAD_DIR, filename), 'wb') as f:
                         f.write(gf.read())