diff --git a/scripts/acme_provider.py b/scripts/acme_provider.py
index 4fbac07..cc34f90 100755
--- a/scripts/acme_provider.py
+++ b/scripts/acme_provider.py
@@ -170,7 +170,8 @@ def certbot_prefix(executable: str | None = None) -> list[str]:
         return [executable]
     managed_python = os.environ.get("RUSTPROXY_CERTBOT_PYTHON")
     if managed_python:
-        return [managed_python, "-I", "-m", "certbot"]
+        managed_certbot = str(Path(managed_python).with_name("certbot"))
+        return [managed_python, "-I", managed_certbot]
     discovered = shutil.which("certbot")
     if discovered:
         return [discovered]
diff --git a/src/acme/runtime_env.rs b/src/acme/runtime_env.rs
index bf385f5..64060d5 100644
--- a/src/acme/runtime_env.rs
+++ b/src/acme/runtime_env.rs
@@ -145,8 +145,9 @@ async fn managed_environment_valid(
     if !command_success(imports, Duration::from_secs(20), shutdown).await {
         return false;
     }
+    let certbot = venv_bin(directory).join("certbot");
     let mut version = Command::new(&python);
-    version.args(["-I", "-m", "certbot", "--version"]);
+    version.arg("-I").arg(certbot).arg("--version");
     command_success(version, Duration::from_secs(20), shutdown).await
 }