diff --git a/dataframe_image/_browser_pdf.py b/dataframe_image/_browser_pdf.py
index 936a08e..f2da203 100644
--- a/dataframe_image/_browser_pdf.py
+++ b/dataframe_image/_browser_pdf.py
@@ -88,7 +88,7 @@ def launch_chrome():
         "--remote-debugging-port=9222",
         f"--crash-dumps-dir={temp_dir.name}",
     ]
-    if os.environ["NO_SANDBOX"] or platform.system().lower() != "windows" and os.geteuid() == 0:
+    if os.environ.get("NO_SANDBOX", False) or platform.system().lower() != "windows" and os.geteuid() == 0:
         args.append("--no-sandbox")
     p = Popen(args=args)
     return p
diff --git a/dataframe_image/_screenshot.py b/dataframe_image/_screenshot.py
index 4c6c07d..80c4e92 100644
--- a/dataframe_image/_screenshot.py
+++ b/dataframe_image/_screenshot.py
@@ -127,7 +127,7 @@ def take_screenshot(self, ss_width=1400, ss_height=900):
                 f"--force-device-scale-factor={self.device_scale_factor}",
             ]
             # root user needs no-sandbox
-            if os.environ["NO_SANDBOX"] or platform.system().lower() != "windows" and os.geteuid() == 0:
+            if os.environ.get("NO_SANDBOX", False) or platform.system().lower() != "windows" and os.geteuid() == 0:
                 args.append("--no-sandbox")
 
             if ss_width and ss_height: