diff --git a/test/alterschema/CMakeLists.txt b/test/alterschema/CMakeLists.txt
index a488fe616..d6e09f7fa 100644
--- a/test/alterschema/CMakeLists.txt
+++ b/test/alterschema/CMakeLists.txt
@@ -27,3 +27,13 @@ target_link_libraries(sourcemeta_core_alterschema_unit
   PRIVATE sourcemeta::core::jsonschema)
 target_link_libraries(sourcemeta_core_alterschema_unit
   PRIVATE sourcemeta::core::alterschema)
+
+sourcemeta_executable(NAMESPACE sourcemeta PROJECT core
+  NAME alterschema_canonicalize
+  SOURCES alterschema_canonicalize.cc)
+target_link_libraries(sourcemeta_core_alterschema_canonicalize
+  PRIVATE sourcemeta::core::json)
+target_link_libraries(sourcemeta_core_alterschema_canonicalize
+  PRIVATE sourcemeta::core::jsonschema)
+target_link_libraries(sourcemeta_core_alterschema_canonicalize
+  PRIVATE sourcemeta::core::alterschema)
diff --git a/test/alterschema/alterschema_canonicalize.cc b/test/alterschema/alterschema_canonicalize.cc
new file mode 100644
index 000000000..f390a24f2
--- /dev/null
+++ b/test/alterschema/alterschema_canonicalize.cc
@@ -0,0 +1,35 @@
+#include <sourcemeta/core/alterschema.h>
+#include <sourcemeta/core/json.h>
+#include <sourcemeta/core/jsonschema.h>
+
+#include <cstdlib>  // EXIT_SUCCESS, EXIT_FAILURE
+#include <iostream> // std::cerr, std::cout
+
+auto main(int argc, char *argv[]) -> int {
+  if (argc != 2) {
+    std::cerr << "Usage: " << argv[0] << " <schema.json>\n";
+    return EXIT_FAILURE;
+  }
+
+  auto document{sourcemeta::core::read_json(argv[1])};
+
+  sourcemeta::core::SchemaTransformer bundle;
+  sourcemeta::core::add(bundle,
+                        sourcemeta::core::AlterSchemaMode::Canonicalizer);
+  const auto result{bundle.apply(document, sourcemeta::core::schema_walker,
+                                 sourcemeta::core::schema_resolver,
+                                 [](const auto &pointer, const auto &name,
+                                    const auto &message, const auto &) {
+                                   std::cerr
+                                       << sourcemeta::core::to_string(pointer)
+                                       << ": " << name << ": " << message
+                                       << "\n";
+                                 })};
+
+  sourcemeta::core::format(document, sourcemeta::core::schema_walker,
+                           sourcemeta::core::schema_resolver);
+  sourcemeta::core::prettify(document, std::cout);
+  std::cout << "\n";
+
+  return result.first ? EXIT_SUCCESS : EXIT_FAILURE;
+}