diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index adfb1829..bdb16545 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -383,7 +383,7 @@ jobs:
               git \
               png
           run: | # FreeBSD `c++` compiler does not support `make develop` sanitizers ASan or UBSan
-            cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug -DCMAKE_CXX_COMPILER=c++ -DUSE_EXTERNAL_TESTS=OFF -DOS=bsd
+            cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug -DCMAKE_CXX_COMPILER=c++ -DUSE_EXTERNAL_TESTS=OFF -DTESTS_OS_NAME=bsd
             cmake --build build -j4 --verbose
             cmake --install build --verbose
             cmake --build build --target test
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index b054f586..6cebac57 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -2,15 +2,21 @@
 
 option(USE_NONFREE_TESTS "run tests that build nonfree codebases" ON)
 option(USE_EXTERNAL_TESTS "run tests that build external codebases" ON)
+set(TESTS_OS_NAME "" CACHE STRING "skip running tests known to fail on this OS")
 
+set(ONLY_FREE)
 if(NOT USE_NONFREE_TESTS)
   set(ONLY_FREE "--only-free")
 endif()
+
+set(ONLY_INTERNAL)
 if(NOT USE_EXTERNAL_TESTS)
   set(ONLY_INTERNAL "--only-internal")
 endif()
-if(DEFINED OS)
-  set(OS_NAME "--os" "${OS}")
+
+set(OS_NAME)
+if(NOT TESTS_OS_NAME STREQUAL "")
+  set(OS_NAME "--os" "${TESTS_OS_NAME}")
 endif()
 
 add_executable(randtilegen gfx/randtilegen.cpp)
diff --git a/test/run-tests.sh b/test/run-tests.sh
index 495956e0..f49e7436 100755
--- a/test/run-tests.sh
+++ b/test/run-tests.sh
@@ -134,6 +134,7 @@ test_downstream pinobatch libbet  all      libbet.gb f117089aa056600e2d404bbcbac
 test_downstream LIJI32    SameBoy bootroms build/bin/BootROMs/cgb_boot.bin 113903775a9d34b798c2f8076672da6626815a91
 # gb-starter kit fails with any `make` on Windows: https://codeberg.org/ISSOtm/gb-starter-kit/issues/1
 # gb-starter-kit fails with macOS/BSD `make`: https://codeberg.org/ISSOtm/gb-starter-kit/issues/29
-if [[ "${osname%-*}" != "windows" && "${osname%-*}" != "macos" && "${osname%-*}" != "bsd" ]]; then
-	test_downstream ISSOtm gb-starter-kit all bin/boilerplate.gb b4f130169ba73284e0d0e71b53e7baa4eca2f7fe
-fi
+case "${osname%%-*}" in
+	windows | macos | bsd) ;;
+	*) test_downstream ISSOtm gb-starter-kit all bin/boilerplate.gb b4f130169ba73284e0d0e71b53e7baa4eca2f7fe;;
+esac