diff --git a/scripts/dev/update_3rdparty.py b/scripts/dev/update_3rdparty.py
index f836492d0..5895bd177 100755
--- a/scripts/dev/update_3rdparty.py
+++ b/scripts/dev/update_3rdparty.py
@@ -66,7 +66,8 @@ def update_pdfjs(target_version=None):
         url = ('https://github.com/mozilla/pdf.js/releases/download/'
                'v{0}/pdfjs-{0}-dist.zip').format(target_version)
 
-    os.chdir(os.path.join(os.path.dirname(sys.argv[0]), '..', '..'))
+    os.chdir(os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                          '..', '..'))
     target_path = os.path.join('qutebrowser', '3rdparty', 'pdfjs')
     print("=> Downloading pdf.js {}".format(version))
     try: