diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 2f2b3be4..663bf0fb 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -17,6 +17,7 @@ Change log
 **Bug fix**
 
 - Value propagation of string tensors no longer raises an erroneous ``ValueError`` in some instances.
+- Apply custom shape inference logic in :func:`spox.opsets.ai.onnx.v19.loop` and :func:`spox.opsets.ai.onnx.v21.loop`.
 
 
 0.12.1 (2024-06-18)
diff --git a/src/spox/opset/ai/onnx/v19.py b/src/spox/opset/ai/onnx/v19.py
index 6c14823d..4be48159 100644
--- a/src/spox/opset/ai/onnx/v19.py
+++ b/src/spox/opset/ai/onnx/v19.py
@@ -617,6 +617,20 @@ class Inputs(BaseInputs):
     class Outputs(BaseOutputs):
         v_final_and_scan_outputs: Sequence[Var]
 
+    def infer_output_types(self) -> dict[str, Type]:
+        output_types = super().infer_output_types()
+
+        body = self.attrs.body.value
+        n = len(body.requested_arguments) - 2
+
+        carried_names = list(self.outputs.get_vars())[:n]
+        carried_types = [v.type for v in list(body.requested_results.values())[1:][:n]]
+
+        for name, typ in zip(carried_names, carried_types):
+            output_types[name] = typ
+
+        return output_types
+
     op_type = OpType("Loop", "", 19)
 
     attrs: Attributes
diff --git a/src/spox/opset/ai/onnx/v21.py b/src/spox/opset/ai/onnx/v21.py
index f4f027cc..0c93face 100644
--- a/src/spox/opset/ai/onnx/v21.py
+++ b/src/spox/opset/ai/onnx/v21.py
@@ -612,6 +612,20 @@ class Inputs(BaseInputs):
     class Outputs(BaseOutputs):
         v_final_and_scan_outputs: Sequence[Var]
 
+    def infer_output_types(self) -> dict[str, Type]:
+        output_types = super().infer_output_types()
+
+        body = self.attrs.body.value
+        n = len(body.requested_arguments) - 2
+
+        carried_names = list(self.outputs.get_vars())[:n]
+        carried_types = [v.type for v in list(body.requested_results.values())[1:][:n]]
+
+        for name, typ in zip(carried_names, carried_types):
+            output_types[name] = typ
+
+        return output_types
+
     op_type = OpType("Loop", "", 21)
 
     attrs: Attributes
diff --git a/tests/type_inference/test_loop.py b/tests/type_inference/test_loop.py
index c193d519..e99c92e7 100644
--- a/tests/type_inference/test_loop.py
+++ b/tests/type_inference/test_loop.py
@@ -1,11 +1,16 @@
 # Copyright (c) QuantCo 2023-2024
 # SPDX-License-Identifier: BSD-3-Clause
 
-import spox.opset.ai.onnx.v17 as op
+import pytest
+
+import spox.opset.ai.onnx.v17 as op17
+import spox.opset.ai.onnx.v19 as op19
+import spox.opset.ai.onnx.v21 as op21
 from spox import Tensor, argument
 
 
-def test_loop_inference():
+@pytest.mark.parametrize("op", [op17, op19, op21])
+def test_loop_inference(op):
     x, y, zs = op.loop(
         v_initial=[argument(Tensor(float, (None,))), argument(Tensor(int, ("N", 2)))],
         body=lambda i, c, a, b: [op.const(True), a, op.add(i, b), i],
diff --git a/tools/generate_opset.py b/tools/generate_opset.py
index 399a311f..efc9d09b 100644
--- a/tools/generate_opset.py
+++ b/tools/generate_opset.py
@@ -688,7 +688,7 @@ def main(
         "ai.onnx",
         19,
         extras=["const"],
-        type_inference={"Compress": "compress11"},
+        type_inference={"Loop": "loop16-fix"},
         value_propagation={"Constant": "constant13"},
         out_variadic_solutions=V18_OUT_VARIADIC_SOLUTIONS,
         subgraphs_solutions=V16_SUBGRAPH_SOLUTIONS,
@@ -711,6 +711,7 @@ def main(
         "ai.onnx",
         21,
         extras=["const"],
+        type_inference={"Loop": "loop16-fix"},
         value_propagation={"Constant": "constant13"},
         out_variadic_solutions=V18_OUT_VARIADIC_SOLUTIONS,
         subgraphs_solutions=V16_SUBGRAPH_SOLUTIONS,