diff --git a/pymc/model/core.py b/pymc/model/core.py
index 87b4df23f..b85cc802f 100644
--- a/pymc/model/core.py
+++ b/pymc/model/core.py
@@ -34,7 +34,7 @@
 
 from pytensor.compile import DeepCopyOp, Function, get_mode
 from pytensor.compile.sharedvalue import SharedVariable
-from pytensor.graph.basic import Constant, Variable, graph_inputs
+from pytensor.graph.basic import Constant, Variable, ancestors, graph_inputs
 from pytensor.tensor.random.op import RandomVariable
 from pytensor.tensor.random.type import RandomType
 from pytensor.tensor.variable import TensorConstant, TensorVariable
@@ -1241,15 +1241,13 @@ def register_rv(
             self.add_named_variable(rv_var, dims)
             self.set_initval(rv_var, initval)
         else:
-            if (
-                isinstance(observed, TensorVariable)
-                and observed.owner is not None
-                and isinstance(observed.owner.op, MinibatchOp)
-                and total_size is None
-            ):
-                warnings.warn(
-                    f"total_size not provided for observed variable `{name}` that uses pm.Minibatch"
-                )
+            if total_size is None and isinstance(observed, TensorVariable):
+                for node in ancestors([observed]):
+                    if node.owner is not None and isinstance(node.owner.op, MinibatchOp):
+                        warnings.warn(
+                            f"total_size not provided for observed variable `{name}` that uses pm.Minibatch"
+                        )
+                        break
             if not is_valid_observed(observed):
                 raise TypeError(
                     "Variables that depend on other nodes cannot be used for observed data."