diff --git a/src/poetry/packages/locker.py b/src/poetry/packages/locker.py
index e57e60b83b7..7cfdcc10c9f 100644
--- a/src/poetry/packages/locker.py
+++ b/src/poetry/packages/locker.py
@@ -127,6 +127,7 @@ def locked_repository(self) -> Repository:
                 source_url=url,
                 source_reference=source.get("reference"),
                 source_resolved_reference=source.get("resolved_reference"),
+                source_subdirectory=source.get("subdirectory"),
             )
             package.description = info.get("description", "")
             package.category = info.get("category", "main")
@@ -620,6 +621,9 @@ def _dump_package(self, package: Package) -> dict[str, Any]:
             if package.source_resolved_reference:
                 data["source"]["resolved_reference"] = package.source_resolved_reference
 
+            if package.source_subdirectory:
+                data["source"]["subdirectory"] = package.source_subdirectory
+
             if package.source_type in ["directory", "git"]:
                 data["develop"] = package.develop