diff --git a/remotefilelog/remotefilelogserver.py b/remotefilelog/remotefilelogserver.py
--- a/remotefilelog/remotefilelogserver.py
+++ b/remotefilelog/remotefilelogserver.py
@@ -385,7 +385,10 @@
     """
     flog = filectx.filelog()
     frev = filectx.filerev()
-    revlogflags = flog.flags(frev)
+    if util.safehasattr(flog, 'flags'):
+        revlogflags = flog.flags(frev)
+    else:
+        revlogflags = flog._revlog.flags(frev)
     if revlogflags == 0:
         # normal files
         text = filectx.data()
@@ -584,7 +587,7 @@
                 start, length, size, base, linkrev, p1, p2, node = fl.index[cur]
             else:
                 # 4.8
-                base = fl.deltaparent(cur)
+                base = fl._revlog.deltaparent(cur)
                 linkrev = fl.linkrev(cur)
                 node = fl.node(cur)
                 p1, p2 = fl.parentrevs(cur)