diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -2337,7 +2337,15 @@
 
         curr = len(self)
         prev = curr - 1
-        offset = self.end(prev)
+        if self.version & 0xFFFF == REVLOGV2:
+            prev_node = self.index[prev]
+            sidedata_offset = prev_node[10]
+            if sidedata_offset == 0:
+                offset = self.end(prev)
+            else:
+                offset = sidedata_offset + prev_node[11]
+        else:
+            offset = self.end(prev)
         p1r, p2r = self.rev(p1), self.rev(p2)
 
         # full versions are inserted when the needed deltas