diff --git a/av1/common/mvref_common.c b/av1/common/mvref_common.c
index 2202fb5..8b55260 100644
--- a/av1/common/mvref_common.c
+++ b/av1/common/mvref_common.c
@@ -1845,7 +1845,7 @@
   }
 
   if (alt_frame_index > cur_frame_index && ref_stamp >= 0)
-    motion_field_projection(cm, ALTREF_FRAME, 2);
+    motion_field_projection(cm, ALTREF_FRAME, ref_stamp);
 }
 #endif  // CONFIG_MFMV