diff --git a/gui/app.py b/gui/app.py
index ea13651..d8f840f 100644
--- a/gui/app.py
+++ b/gui/app.py
@@ -118,7 +118,7 @@ def gen_keypair_psk():
 def to_png_b64(text):
     img = qrcode.make(text)
     buf = io.BytesIO()
-    img.save(buf, format="PNG")
+    img.save(buf)
     return base64.b64encode(buf.getvalue()).decode("ascii")