diff --git a/contrib/schemagen/CMakeLists.txt b/contrib/schemagen/CMakeLists.txt
index 7cae8eb..bb50128 100644
--- a/contrib/schemagen/CMakeLists.txt
+++ b/contrib/schemagen/CMakeLists.txt
@@ -12,6 +12,8 @@ add_test(
 set(SCHEMAGEN_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/weaseljson_schemagen.py)
 set(EXAMPLE_SCHEMA ${CMAKE_CURRENT_SOURCE_DIR}/example.schema.json)
 set(GEN_H ${CMAKE_CURRENT_BINARY_DIR}/gen.h)
+set(BIG_SCHEMA ${CMAKE_CURRENT_SOURCE_DIR}/big.schema.json)
+set(BIG_H ${CMAKE_CURRENT_BINARY_DIR}/big.h)
 
 add_custom_command(
   OUTPUT ${GEN_H}
@@ -20,7 +22,15 @@ add_custom_command(
   DEPENDS ${SCHEMAGEN_SCRIPT} ${EXAMPLE_SCHEMA}
   COMMENT "Generating gen.h from example.schema.json")
 
+add_custom_command(
+  OUTPUT ${BIG_H}
+  COMMAND ${Python3_EXECUTABLE} ${SCHEMAGEN_SCRIPT} ${BIG_SCHEMA} -o ${BIG_H}
+          --namespace big_schema
+  DEPENDS ${SCHEMAGEN_SCRIPT} ${BIG_SCHEMA}
+  COMMENT "Generating big.h from big.schema.json")
+
 add_custom_target(schemagen_gen_h DEPENDS ${GEN_H})
+add_custom_target(schemagen_big_h DEPENDS ${BIG_H})
 
 add_executable(schemagen_example ${CMAKE_CURRENT_SOURCE_DIR}/test_gen.cpp)
 target_include_directories(schemagen_example
@@ -29,7 +39,19 @@ target_link_libraries(schemagen_example PRIVATE ${PROJECT_NAME})
 target_compile_options(schemagen_example PRIVATE -Wno-switch-enum)
 add_dependencies(schemagen_example schemagen_gen_h)
 
+add_executable(schemagen_big ${CMAKE_CURRENT_SOURCE_DIR}/test_big.cpp)
+target_include_directories(schemagen_big PRIVATE include
+                                                 ${CMAKE_CURRENT_BINARY_DIR})
+target_link_libraries(schemagen_big PRIVATE ${PROJECT_NAME})
+target_compile_options(schemagen_big PRIVATE -Wno-switch-enum)
+add_dependencies(schemagen_big schemagen_big_h)
+
 add_test(
   NAME schemagen_example
   COMMAND schemagen_example
   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
+add_test(
+  NAME schemagen_big
+  COMMAND schemagen_big
+  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
diff --git a/contrib/schemagen/README.md b/contrib/schemagen/README.md
index 7c96b6f..7232abb 100644
--- a/contrib/schemagen/README.md
+++ b/contrib/schemagen/README.md
@@ -76,15 +76,25 @@ union `type` lists other than `["T", "null"]`, non-string enums, and remote
 
 ## Testing
 
-After building weaseljson (e.g. `cmake -S . -B build && make -C build`), run:
+The schemagen tests are registered with CTest and run as part of the default
+`ctest` invocation from the build directory:
+
+```sh
+cmake -S . -B build
+make -C build -j "$(nproc)"
+cd build
+ctest --output-on-failure
+```
+
+For local development you can also use the convenience script:
 
 ```sh
 cd contrib/schemagen
 ./run_tests.sh
 ```
 
-This regenerates the example parser (`gen.h`) and a regression parser with 40
-required properties (`big.h`), compiles `test_gen.cpp` and `test_big.cpp`, and
-runs both. `test_big.cpp` specifically covers issue #3: it checks that a
-40-property object accepts all fields, rejects a missing field at index 32, and
-rejects duplicate keys around the 32-bit boundary.
+Both regenerate the example parser (`gen.h`) and a regression parser with 40
+required properties (`big.h`), compile `test_gen.cpp` and `test_big.cpp`, and run
+them. `test_big.cpp` specifically covers issue #3: it checks that a 40-property
+object accepts all fields, rejects a missing field at index 32, and rejects
+duplicate keys around the 32-bit boundary.