diff --git a/lib/streaming_providers/base/ui/qr_generator.py b/lib/streaming_providers/base/ui/qr_generator.py
index e1d9506..1194f8f 100644
--- a/lib/streaming_providers/base/ui/qr_generator.py
+++ b/lib/streaming_providers/base/ui/qr_generator.py
@@ -43,9 +43,10 @@ def generate_qr_code_png(data: str, size: int = 512) -> Optional[bytes]:
         # Generate image using pure Python PNG backend
         img = qr.make_image(image_factory=PyPNGImage, fill_color="black", back_color="white")
 
-        # Convert to PNG bytes
+        # Convert to PNG bytes. PyPNGImage.save() always writes PNG and does
+        # not accept a `format` kwarg (unlike PIL), so it must be omitted here.
         buffer = io.BytesIO()
-        img.save(buffer, format="PNG")
+        img.save(buffer)
         png_data = buffer.getvalue()
 
         return png_data
diff --git a/requirements.txt b/requirements.txt
index a4641c5..dbb4ffb 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -17,6 +17,12 @@ requests~=2.32.5
 Unidecode~=1.3.7
 PyYAML~=6.0.3
 
+# QR-code login (magenta2 SAM3 remote login). pypng provides qrcode's pure
+# Python PNG backend so no Pillow/system image libs are required in the
+# standalone/Docker runtime.
+qrcode>=7.4
+pypng>=0.0.21
+
 # Optional but recommended
 aiohttp>=3.8.5
 cryptography>=41.0.4