diff --git a/test/clang-tidy/Inputs/bugprone-not-null-terminated-result/not-null-terminated-result-c.h b/test/clang-tidy/Inputs/bugprone-not-null-terminated-result/not-null-terminated-result-c.h
index 9a29112..b99169f 100644
--- a/test/clang-tidy/Inputs/bugprone-not-null-terminated-result/not-null-terminated-result-c.h
+++ b/test/clang-tidy/Inputs/bugprone-not-null-terminated-result/not-null-terminated-result-c.h
@@ -13,7 +13,7 @@
 
 #pragma clang system_header
 
-typedef unsigned int size_t;
+typedef __typeof__(sizeof(int)) size_t;
 typedef int errno_t;
 
 size_t strlen(const char *str);