diff --git a/src/e3/electrolyt/plan.py b/src/e3/electrolyt/plan.py
index 1a084b80..df75be0d 100644
--- a/src/e3/electrolyt/plan.py
+++ b/src/e3/electrolyt/plan.py
@@ -272,6 +272,7 @@ def execute(
         if entry_point_parameters is None:
             entry_point_parameters = {}
 
+        nb_entry_points = len(plan.entry_points)
         if entry_point_name in plan.entry_points:
             plan.entry_points[entry_point_name].execute(**entry_point_parameters)
         else:
@@ -279,6 +280,14 @@ def execute(
             # used everywhere
             plan.mod.__dict__[entry_point_name](**entry_point_parameters)
 
+        if len(plan.entry_points) != nb_entry_points:
+            # The number of entry points should not change when executing the
+            # code in an entry point. If it does, it means that there is a
+            # nested entry point, this is not supported.
+            raise PlanError(
+                f"the plan contains nested entry points in {entry_point_name}"
+            )
+
         return self.action_list
 
     def _add_action(self, name: str, *args: Any, **kwargs: Any) -> None:
diff --git a/tests/tests_e3/electrolyt/plan/main_test.py b/tests/tests_e3/electrolyt/plan/main_test.py
index 50e5a080..26587258 100644
--- a/tests/tests_e3/electrolyt/plan/main_test.py
+++ b/tests/tests_e3/electrolyt/plan/main_test.py
@@ -2,6 +2,7 @@
 import e3.electrolyt.host as host
 import e3.electrolyt.plan as plan
 import e3.env
+import pytest
 
 
 def build_action(spec, build=None, host=None, target=None, board=None):
@@ -145,6 +146,33 @@ def test_entry_points():
     assert ep_executed[0].name == "machine2"
 
 
+def test_nested_entry_points():
+    """Test a plan containing nested entry points.
+
+    Nested entry points are not supported, verify that we get an Plan Error.
+    """
+    plan_content = [
+        '@machine(name="machine1", description="Machine 1",',
+        '         platform="x86_64-linux", version="rhES6")',
+        "def machine1():",
+        '    build("a")',
+        '    @machine(description="Machine 2",',
+        '             platform="x86_64-linux", version="rhES6")',
+        "    def machine2():",
+        '        build("b")',
+    ]
+    myplan = _get_plan({}, plan_content)
+
+    db = myplan.entry_points
+    assert len(db) == 1
+    assert "machine1" in db
+
+    context = _get_new_plancontext("machine1")
+    with pytest.raises(plan.PlanError) as pe:
+        context.execute(myplan, "machine1")
+    assert "nested" in str(pe)
+
+
 def test_plan_disable_lines():
     """Check that lines in enabled=False blocks are disabled."""
     context = _get_new_plancontext("myserver")