diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index ba78a07834..612bb03862 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -107,6 +107,7 @@ set(CMAKE_REQUIRED_LINK_OPTIONS "-fsanitize=fuzzer")
 set(CMAKE_REQUIRED_FLAGS "-fsanitize=fuzzer-no-link")
 check_cxx_source_compiles([[
 #include <cstdint>
+#include <cstddef>
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, std::size_t Size) {
   return 0;
 }