diff --git a/src/learn/sfen_packer.cpp b/src/learn/sfen_packer.cpp
index 236c875f..791870ca 100644
--- a/src/learn/sfen_packer.cpp
+++ b/src/learn/sfen_packer.cpp
@@ -386,7 +386,7 @@ namespace Learner {
     pos.thisThread = th;
     pos.set_state(pos.st);
 
-    assert(pos_is_ok());
+    assert(pos.pos_is_ok());
 
     return 0;
   }