diff --git a/upstream-info/lwip.yaml b/upstream-info/lwip.yaml
index ce814e85b7dfc34666ec49b781d1d300f93be93c..9ff75b503e07d19454d7a63349ce4e96553df732 100644
--- a/upstream-info/lwip.yaml
+++ b/upstream-info/lwip.yaml
@@ -2,7 +2,7 @@
 version_control: git
 src_repo: https://git.savannah.gnu.org/git/lwip.git
 tag_pattern: STABLE-(.*)_RELEASE
-separator: ""
+separator: "_"
 git_url: https://git.savannah.gnu.org/git/lwip.git
 git_tag:
 - STABLE-2_1_2_RELEASE