diff --git a/hgext/remotefilelog/fileserverclient.py b/hgext/remotefilelog/fileserverclient.py
--- a/hgext/remotefilelog/fileserverclient.py
+++ b/hgext/remotefilelog/fileserverclient.py
@@ -495,7 +495,7 @@
                 _(b"connection closed early"),
             )
         size = int(line)
-        data = pipe.read(size)
+        data = _readhugestream(pipe, size)
         if len(data) != size:
             raise error.ResponseError(
                 _(b"error downloading file contents:"),
@@ -664,3 +664,21 @@
             b'excess remotefilelog fetching:\n%s\n',
             b''.join(pycompat.sysbytes(s) for s in traceback.format_stack()),
         )
+
+
+if pycompat.iswindows:
+    # read() deadlock on Windows when size is too big
+    def _readhugestream(stream, size):
+        maxchunksize = 4 * 1024
+        data = bytearray()
+
+        while len(data) < size:
+            datachunk = stream.read(min(size - len(data), maxchunksize))
+            data += datachunk
+            if not datachunk:
+                # Prevents a deadlock in case the pipe is empty
+                break
+        return pycompat.bytestr(data)
+else:
+    def _readhugestream(stream, size):
+        return stream.read(size)