diff --git a/src/poetry/utils/env/script_strings.py b/src/poetry/utils/env/script_strings.py
index 246649867f3..3e663e3e0c6 100644
--- a/src/poetry/utils/env/script_strings.py
+++ b/src/poetry/utils/env/script_strings.py
@@ -82,7 +82,7 @@ def _version_nodot(version):
     "platform_release": platform.release(),
     "platform_system": platform.system(),
     "platform_version": platform.version(),
-    "python_full_version": platform.python_version(),
+    "python_full_version": platform.python_version().rstrip("+"),
     "platform_python_implementation": platform.python_implementation(),
     "python_version": ".".join(platform.python_version_tuple()[:2]),
     "sys_platform": sys.platform,
diff --git a/src/poetry/utils/env/system_env.py b/src/poetry/utils/env/system_env.py
index 8ddef7b5608..81396206ff3 100644
--- a/src/poetry/utils/env/system_env.py
+++ b/src/poetry/utils/env/system_env.py
@@ -71,7 +71,8 @@ def get_marker_env(self) -> dict[str, Any]:
             "platform_release": platform.release(),
             "platform_system": platform.system(),
             "platform_version": platform.version(),
-            "python_full_version": platform.python_version(),
+            # Workaround for https://github.com/python/cpython/issues/99968
+            "python_full_version": platform.python_version().rstrip("+"),
             "platform_python_implementation": platform.python_implementation(),
             "python_version": ".".join(platform.python_version().split(".")[:2]),
             "sys_platform": sys.platform,
diff --git a/tests/utils/env/test_system_env.py b/tests/utils/env/test_system_env.py
new file mode 100644
index 00000000000..4e71a2c595c
--- /dev/null
+++ b/tests/utils/env/test_system_env.py
@@ -0,0 +1,19 @@
+from __future__ import annotations
+
+import sys
+
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+from poetry.utils.env import SystemEnv
+
+
+if TYPE_CHECKING:
+    from pytest_mock import MockerFixture
+
+
+def test_get_marker_env_untagged_cpython(mocker: MockerFixture) -> None:
+    mocker.patch("platform.python_version", return_value="3.11.9+")
+    env = SystemEnv(Path(sys.prefix))
+    marker_env = env.get_marker_env()
+    assert marker_env["python_full_version"] == "3.11.9"