--- a/migen/fhdl/tracer.py
+++ b/migen/fhdl/tracer.py
@@ -38,6 +38,7 @@ _load_build_opcodes = {
     "BUILD_LIST" : _bytecode_length_version_guard(3),
     "CACHE" : _bytecode_length_version_guard(3),
     "COPY" : _bytecode_length_version_guard(3),
+    "LOAD_FAST_BORROW" : _bytecode_length_version_guard(3),
 }