diff --git a/hdl21/flatten.py b/hdl21/flatten.py
index 5609810..ea787d5 100644
--- a/hdl21/flatten.py
+++ b/hdl21/flatten.py
@@ -89,7 +89,7 @@ def _find_signal_or_port(m: h.Module, name: str) -> h.Signal:
 def is_flat(m: Union[h.Instance, h.Instantiable]) -> bool:
     if isinstance(m, h.Instance):
         return is_flat(m.of)
-    elif isinstance(m, (h.PrimitiveCall, h.GeneratorCall, h.ExternalModuleCall)):
+    elif isinstance(m, (h.PrimitiveCall, h.ExternalModuleCall)):
         return True
     elif isinstance(m, h.Module):
         insts = m.instances.values()
diff --git a/hdl21/tests/test_flatten.py b/hdl21/tests/test_flatten.py
index d07f9f8..913354f 100644
--- a/hdl21/tests/test_flatten.py
+++ b/hdl21/tests/test_flatten.py
@@ -149,34 +149,3 @@ class M:
 
     flattened = flatten(M)
 
-
-def test_flatten_generator():
-    """Flatten a Generator
-    (And it has Concat too! Kinda. But not by the point flattening happens)."""
-
-    @h.paramclass
-    class Params:
-        how_many = h.Param(dtype=int, default=5, desc="How many inverters you want?")
-
-    @h.generator
-    def Gen(params: Params) -> h.Module:
-        if params.how_many < 2:
-            raise ValueError
-
-        @h.module
-        class M:
-            vdd, vss, vin, vout = h.Ports(4)
-            internal_signal = h.Signal(width=params.how_many - 1)
-            # Array of `how_many` series-connected inverters
-            invs = params.how_many * Inverter(
-                vdd=vdd,
-                vss=vss,
-                vin=h.Concat(vin, internal_signal),
-                vout=h.Concat(internal_signal, vout),
-            )
-
-        return M
-
-    gen5 = Gen(how_many=5)
-    assert not is_flat(gen5)
-    flattened = flatten(gen5)