diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5e2215f19..0bae125d7 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -35,6 +35,8 @@ jobs:
       - name: Install lavapipe for the GPU execution tests
         run: sudo apt-get update && sudo apt-get install -y --no-install-recommends libvulkan1 mesa-vulkan-drivers
       - run: cmake -S . -B build $CONFIGURE -DANYPS5_ENABLE_SPIRV_TOOLS=ON
+      - name: Check that every test executable is registered with ctest
+        run: python3 tools/check_test_registration.py build
       - run: cmake --build build
       - run: cmake --build build --target libs
       - run: ctest --test-dir build --output-on-failure --timeout 120 --repeat until-fail:3
@@ -73,6 +75,9 @@ jobs:
           evict-old-files: job
       - shell: cmd
         run: cmake -S . -B build %CONFIGURE%
+      - name: Check that every test executable is registered with ctest
+        shell: cmd
+        run: python tools/check_test_registration.py build
       - shell: cmd
         run: cmake --build build
       - shell: cmd
diff --git a/tools/check_test_registration.py b/tools/check_test_registration.py
new file mode 100644
index 000000000..4931f8836
--- /dev/null
+++ b/tools/check_test_registration.py
@@ -0,0 +1,68 @@
+import argparse
+import re
+import subprocess
+from pathlib import Path
+
+TEST_OUTPUT = "tests/"
+
+KNOWN_UNRUN = {
+    "agc_driver_bda_device_tests",
+    "agc_driver_mesh_tests",
+    "agc_driver_recorder_tests",
+    "guest_formatting_tests",
+    "video_out_flip_tests",
+}
+
+
+def built(build):
+    listed = subprocess.run(["ninja", "-C", str(build), "-t", "targets", "all"],
+                            capture_output=True, text=True, check=True).stdout
+    names = set()
+    for line in listed.splitlines():
+        found = re.match(rf"^{TEST_OUTPUT}([A-Za-z0-9_]+)(?::|\s|$)", line)
+        if found:
+            names.add(found.group(1))
+    return names
+
+
+def registered(build):
+    names = set()
+    for file in Path(build).rglob("CTestTestfile.cmake"):
+        for line in file.read_text(errors="replace").splitlines():
+            found = re.match(r"\s*add_test\s*\((.*)\)\s*$", line)
+            if not found:
+                continue
+            for token in re.findall(r'"([^"]*)"|(\S+)', found.group(1)):
+                argument = token[0] or token[1]
+                base = re.split(r"[\\/]", argument)[-1]
+                if base.endswith(".exe"):
+                    base = base[:-4]
+                if base:
+                    names.add(base)
+    return names
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="fail when a test executable is built that no ctest test runs")
+    parser.add_argument("build", type=Path, nargs="?", default=Path("build"), help="configured build directory")
+    parser.add_argument("--list", action="store_true", help="print every test executable and whether ctest runs it")
+    args = parser.parse_args()
+    every = sorted(built(args.build))
+    run = registered(args.build)
+    if args.list:
+        for name in every:
+            print(f"{'run' if name in run else 'NOT RUN'}  {name}")
+        raise SystemExit
+    unrun = sorted(set(every) - run)
+    if not every:
+        print(f"no test executables found under {args.build}; is it configured with -DBUILD_TESTING=ON?")
+        raise SystemExit(1)
+    for name in sorted(set(unrun) & KNOWN_UNRUN):
+        print(f"note: {name} is built and not run, as recorded")
+    fresh = sorted(set(unrun) - KNOWN_UNRUN)
+    for name in fresh:
+        print(f"error: {name} is built but no ctest test runs it")
+    if fresh:
+        print(f"{len(fresh)} test executable(s) would never run: ctest reports a full pass over what it knows, so a test nobody registered is invisible in CI")
+        raise SystemExit(1)
+    print(f"{len(every)} test executable(s), {len(unrun)} built and not run as recorded, none new")