diff --git a/.github/workflows/pypi.yml b/.github/workflows/pypi.yml
index d89ab404..61a8b690 100644
--- a/.github/workflows/pypi.yml
+++ b/.github/workflows/pypi.yml
@@ -23,8 +23,6 @@ jobs:
         fetch-depth: 0  # We need full history for setuptools_scm to figure out version
     - name: Set safe directory (work around checkout not doing that properly for containers)
       run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
-    - name: Install build dependencies for checktestdata
-      run: yum -y install boost-devel gmp-devel
     - name: Build sdist (and broken wheel)
       run: /opt/python/cp311-cp311/bin/python -m build
     - name: Repair wheel
diff --git a/.gitmodules b/.gitmodules
deleted file mode 100644
index 078706c2..00000000
--- a/.gitmodules
+++ /dev/null
@@ -1,3 +0,0 @@
-[submodule "checktestdata"]
-	path = support/checktestdata
-	url = https://github.com/DOMjudge/checktestdata
diff --git a/Makefile b/Makefile
index bd3337bf..b1f84773 100644
--- a/Makefile
+++ b/Makefile
@@ -1,14 +1,9 @@
-all: checktestdata
+all:
 	make -C support
 
-builddeb: checktestdata
+builddeb:
 	dpkg-buildpackage -us -uc -tc -b
 
-checktestdata: support/checktestdata/bootstrap
-
-support/checktestdata/bootstrap:
-	git submodule update --init
-
 clean:
 	make -C support clean
 	rm -rf problemtools.egg-info build
diff --git a/problemtools/run/checktestdata.py b/problemtools/run/checktestdata.py
index 939c1e30..a8a65fd2 100644
--- a/problemtools/run/checktestdata.py
+++ b/problemtools/run/checktestdata.py
@@ -3,29 +3,24 @@
 """
 
 import os
+import sys
 from .executable import Executable
-from .errors import ProgramError
-from .tools import get_tool_path
 
 
 class Checktestdata(Executable):
     """Wrapper class for running Checktestdata scripts."""
 
-    _CTD_PATH = get_tool_path('checktestdata')
-
     def __init__(self, path):
         """Create a Checktestdata wrapper.
 
         Args:
             path (str): path to .ctd source file
         """
-        if Checktestdata._CTD_PATH is None:
-            raise ProgramError('Could not locate the Checktestdata program to run %s' % path)
-        super().__init__(Checktestdata._CTD_PATH, args=[path])
+        super().__init__(sys.executable, args=['-m', 'checktestdata', path])
 
     def __str__(self) -> str:
         """String representation"""
-        return '%s' % (self.args[0])
+        return '%s' % (self.args[-1])
 
     def do_compile(self) -> tuple[bool, str | None]:
         """Syntax-check the Checktestdata script
diff --git a/pyproject.toml b/pyproject.toml
index 3a99cedc..4e3f4a43 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,6 +19,7 @@ dependencies = [
     "PyYAML",
     "plasTeX>=3.0",
     "pydantic>=2.11",
+    "checktestdata>=2026.7.1",
 ]
 dynamic = [ "version" ]
 
diff --git a/requirements.txt b/requirements.txt
index 6e73c8a7..563e3133 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,3 +3,4 @@ nh3
 PyYAML
 plasTeX>=3.0
 pydantic>=2.11
+checktestdata>=2026.7.1
diff --git a/setup.py b/setup.py
index 5cda9d11..d94164ed 100755
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,6 @@
 
 import setuptools
 import setuptools.command.build
-import setuptools.command.sdist
 
 
 class BuildSupport(setuptools.Command):
@@ -27,22 +26,6 @@ def run(self):
         subprocess.check_call(command)
 
 
-class CheckoutChecktestdata(setuptools.Command):
-    """A custom command to build the support programs."""
-
-    description = 'checkout the git submodule for checktestdata (via make)'
-
-    def initialize_options(self) -> None:
-        pass
-
-    def finalize_options(self) -> None:
-        pass
-
-    def run(self):
-        command = ['make', 'checktestdata']
-        subprocess.check_call(command)
-
-
 # It's *very* unclear from setuptools' documentation what the best way to do this is.
 #
 # I think that the ideal way would be to insert BuildSupport as a SubCommand
@@ -55,20 +38,9 @@ def run(self):
         super().run()
 
 
-# To make python -m build work from a fresh checkout, we also need to hook sdist to
-# do a git submodule checkout so that the source code for checktestdata is included
-# in the sdist (an alternative approach would be to include .git in the sdist (eww).
-class sdist(setuptools.command.sdist.sdist):
-    def run(self):
-        self.run_command('checkout_checktestdata')
-        super().run()
-
-
 setuptools.setup(
     cmdclass={
         'build_support': BuildSupport,
         'build': build,
-        'checkout_checktestdata': CheckoutChecktestdata,
-        'sdist': sdist,
     },
 )
diff --git a/support/Makefile b/support/Makefile
index d90a363b..d1ad9368 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -1,8 +1,7 @@
 PACKAGE=problemtools
-CONF=checktestdata/config.mk
-PROGRAMS=checktestdata default_validator interactive
+PROGRAMS=default_validator interactive
 
-all: $(CONF)
+all:
 	$(foreach prog,$(PROGRAMS),$(MAKE) -C $(prog) &&) true
 
 install: all
@@ -12,14 +11,5 @@ install: all
 	cp viva/viva.jar $(DESTDIR)
 	install viva/viva.sh $(DESTDIR)
 
-$(CONF): checktestdata/bootstrap
-	cd checktestdata && ./bootstrap
-
-checktestdata/bootstrap:
-	git submodule update --init
-
 clean:
 	$(foreach prog,$(PROGRAMS),$(MAKE) -C $(prog) clean;)
-
-distclean: clean
-	rm -f $(CONF)
diff --git a/support/checktestdata b/support/checktestdata
deleted file mode 160000
index 38dda218..00000000
--- a/support/checktestdata
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 38dda218dff402a13319c552f363bbf7444ac1a1