diff --git a/clearml_agent/commands/worker.py b/clearml_agent/commands/worker.py
index 7c9f160..c6588e3 100644
--- a/clearml_agent/commands/worker.py
+++ b/clearml_agent/commands/worker.py
@@ -3569,8 +3569,8 @@ def install_virtualenv(
                     executable_version, executable_version_suffix, executable_name = \
                         self.find_python_executable_for_version(def_python_version)
 
-                self._session.config.put("agent.default_python", executable_version_suffix)
-                self._session.config.put("agent.python_binary", executable_name)
+            self._session.config.put("agent.default_python", executable_version_suffix)
+            self._session.config.put("agent.python_binary", executable_name)
 
         venv_dir = Path(venv_dir) if venv_dir else \
             Path(self._session.config["agent.venvs_dir"], executable_version_suffix)
diff --git a/clearml_agent/helper/package/poetry_api.py b/clearml_agent/helper/package/poetry_api.py
index 5a6de53..ea790d9 100644
--- a/clearml_agent/helper/package/poetry_api.py
+++ b/clearml_agent/helper/package/poetry_api.py
@@ -40,11 +40,11 @@ def new_func(self, *args, **kwargs):
 
 class PoetryConfig:
 
-    def __init__(self, session, interpreter=None):
+    def __init__(self, session):
         # type: (Session, str) -> None
         self.session = session
         self._log = session.get_logger(__name__)
-        self._python = interpreter or sys.executable
+        self._python = sys.executable  # default, overwritten from session config in initialize()
         self._initialized = False
 
     @property
@@ -88,6 +88,11 @@ def _config(self, *args, **kwargs):
     @_guard_enabled
     def initialize(self, cwd=None):
         if not self._initialized:
+            # use correct python version -- detected in Worker.install_virtualenv() and written to
+            # session
+            if self.session.config.get("agent.python_binary", None):
+                self._python = self.session.config.get("agent.python_binary")
+
             if self.session.config.get("agent.package_manager.poetry_version", None) is not None:
                 version = str(self.session.config.get("agent.package_manager.poetry_version"))