diff --git a/chess/polyglot.py b/chess/polyglot.py
index 44a68caa..a7d6807c 100644
--- a/chess/polyglot.py
+++ b/chess/polyglot.py
@@ -324,7 +324,7 @@ class MemoryMappedReader:
     """Maps a Polyglot opening book to memory."""
 
     def __init__(self, filename: StrOrBytesPath) -> None:
-        fd = os.open(filename, os.O_RDONLY | os.O_BINARY if hasattr(os, "O_BINARY") else os.O_RDONLY)
+        fd = os.open(filename, os.O_RDONLY | getattr(os, "O_BINARY", 0))
         try:
             self.mmap: Union[mmap.mmap, _EmptyMmap] = mmap.mmap(fd, 0, access=mmap.ACCESS_READ)
         except (ValueError, OSError):
diff --git a/chess/syzygy.py b/chess/syzygy.py
index 89f8c259..5ead9922 100644
--- a/chess/syzygy.py
+++ b/chess/syzygy.py
@@ -587,7 +587,7 @@ def __init__(self, path: str, *, variant: Type[chess.Board] = chess.Board) -> No
 
     def init_mmap(self) -> None:
         if self.data is None:
-            fd = os.open(self.path, os.O_RDONLY | os.O_BINARY if hasattr(os, "O_BINARY") else os.O_RDONLY)
+            fd = os.open(self.path, os.O_RDONLY | getattr(os, "O_BINARY", 0))
             try:
                 data = mmap.mmap(fd, 0, access=mmap.ACCESS_READ)
             finally: