--- a/src/poetry/core/vcs/__init__.py
+++ b/src/poetry/core/vcs/__init__.py
@@ -9,8 +9,7 @@
 
 
 def get_vcs(directory: Path) -> Git | None:
-    working_dir = Path.cwd()
-    os.chdir(str(directory.resolve()))
+    cwd = str(directory.resolve())
 
     vcs: Git | None
 
@@ -27,17 +26,21 @@
             vcs = None
         else:
             git_dir = subprocess.check_output(
-                [executable(), "rev-parse", "--show-toplevel"],
+                [executable(), "rev-parse", "--show-prefix"],
                 stderr=subprocess.STDOUT,
                 text=True,
+                cwd=cwd,
                 encoding="utf-8",
             ).strip()
+            git_dir = git_dir.strip()[:-1]  # remove the trailing os.sep
+            if not git_dir:
+                git_dir = cwd
+            else:
+                git_dir = cwd[:-len(git_dir)]
 
             vcs = Git(Path(git_dir))
 
     except (subprocess.CalledProcessError, OSError, RuntimeError):
         vcs = None
-    finally:
-        os.chdir(str(working_dir))
 
     return vcs