diff --git a/Makefile b/Makefile
index 244e20373..7b0d708f9 100644
--- a/Makefile
+++ b/Makefile
@@ -406,6 +406,7 @@ ${_TARGET}_ARG=		${${_TARGET}_ARGS:[0]}
 ensure-stable:
 	@if ! git show-ref --verify --quiet refs/heads/stable/${CORE_ABI}; then \
 		git update-ref refs/heads/stable/${CORE_ABI} refs/remotes/origin/stable/${CORE_ABI}; \
+		git config branch.stable/20.7.merge refs/heads/stable/${CORE_ABI}; \
 	fi
 
 diff: ensure-stable