diff --git a/src/poetry/core/packages/vcs_dependency.py b/src/poetry/core/packages/vcs_dependency.py
index 2d7e10fbc..fec24da44 100644
--- a/src/poetry/core/packages/vcs_dependency.py
+++ b/src/poetry/core/packages/vcs_dependency.py
@@ -42,7 +42,7 @@ def __init__(
             allows_prereleases=True,
             source_type=self._vcs.lower(),
             source_url=self._source,
-            source_reference=branch or tag or rev,
+            source_reference=branch or tag or rev or "HEAD",
             source_resolved_reference=resolved_rev,
             source_subdirectory=directory,
             extras=extras,