diff --git a/tests/extmod/qrio.py b/tests/extmod/qrio.py
index 5e9ed4c12a..53c83706f8 100644
--- a/tests/extmod/qrio.py
+++ b/tests/extmod/qrio.py
@@ -5,7 +5,7 @@ except:
     raise SystemExit
 
 loc = __file__.rsplit("/", 1)[0]
-with open(f"{loc}/data/qr.pgm") as f:
+with open(f"{loc}/data/qr.pgm", "rb") as f:
     content = f.read()[-320 * 240 :]
 
 decoder = qrio.QRDecoder(320, 240)