diff --git a/src/poetry/core/packages/vcs_dependency.py b/src/poetry/core/packages/vcs_dependency.py
index fec24da44..f79e8b7d0 100644
--- a/src/poetry/core/packages/vcs_dependency.py
+++ b/src/poetry/core/packages/vcs_dependency.py
@@ -117,7 +117,7 @@ def base_pep_508_name(self) -> str:
             requirement += f"@{self.reference}"
 
         if self._directory:
-            requirement += f"#subdirectory{self._directory}"
+            requirement += f"#subdirectory={self._directory}"
 
         return requirement