diff --git a/mlir/lib/Bindings/Python/IRCore.cpp b/mlir/lib/Bindings/Python/IRCore.cpp
--- a/mlir/lib/Bindings/Python/IRCore.cpp
+++ b/mlir/lib/Bindings/Python/IRCore.cpp
@@ -785,8 +785,7 @@
   materializedNotes = py::tuple(numNotes);
   for (intptr_t i = 0; i < numNotes; ++i) {
     MlirDiagnostic noteDiag = mlirDiagnosticGetNote(diagnostic, i);
-    py::object pyNoteDiag = py::cast(PyDiagnostic(noteDiag));
-    PyTuple_SET_ITEM(materializedNotes->ptr(), i, pyNoteDiag.ptr());
+    materializedNotes.value()[i] = PyDiagnostic(noteDiag);
   }
   return *materializedNotes;
 }
diff --git a/mlir/test/python/ir/diagnostic_handler.py b/mlir/test/python/ir/diagnostic_handler.py
--- a/mlir/test/python/ir/diagnostic_handler.py
+++ b/mlir/test/python/ir/diagnostic_handler.py
@@ -85,6 +85,23 @@
   assert not handler.had_error
 
 
+# CHECK-LABEL: TEST: testDiagnosticNonEmptyNotes
+@run
+def testDiagnosticNonEmptyNotes():
+  ctx = Context()
+  def callback(d):
+    # CHECK: DIAGNOSTIC:
+    # CHECK:   message='arith.addi' op requires one result
+    # CHECK:   notes=['see current operation: "arith.addi"() : () -> ()']
+    print(f"DIAGNOSTIC:")
+    print(f"  message={d.message}")
+    print(f"  notes={list(map(str, d.notes))}")
+    return True
+  handler = ctx.attach_diagnostic_handler(callback)
+  loc = Location.unknown(ctx)
+  Operation.create('arith.addi', loc=loc).verify()
+  assert not handler.had_error
+
 # CHECK-LABEL: TEST: testDiagnosticCallbackException
 @run
 def testDiagnosticCallbackException():