diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index f481a3cec6d..7866ac01278 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -502,6 +502,7 @@ SnapBuildInitialSnapshotForRepack(SnapBuild *builder)
        StringInfo      buf = makeStringInfo();
 
        Assert(builder->state == SNAPBUILD_CONSISTENT);
+       Assert(builder->building_full_snapshot);
 
        snap = SnapBuildBuildSnapshot(builder);