diff --git a/libc/test/src/__support/OSUtil/linux/x86_64/CMakeLists.txt b/libc/test/src/__support/OSUtil/linux/x86_64/CMakeLists.txt
--- a/libc/test/src/__support/OSUtil/linux/x86_64/CMakeLists.txt
+++ b/libc/test/src/__support/OSUtil/linux/x86_64/CMakeLists.txt
@@ -3,5 +3,7 @@
   SUITE libc_osutil_tests
   SRCS syscall_test.cpp
   DEPENDS
-   libc.src.__support.OSUtil.osutil
+    libc.src.__support.OSUtil.osutil
+  COMPILE_OPTIONS
+    -Wno-unused-variable # Only signature tests, declared variables are unused.
 )