diff --git a/tests/include/test/arguments.h b/tests/include/test/arguments.h
index 8c7dd5a..a975bfa 100644
--- a/tests/include/test/arguments.h
+++ b/tests/include/test/arguments.h
@@ -37,7 +37,7 @@
 
 typedef union {
     size_t len;
-    int32_t s32;
+    intmax_t sint;
 } mbedtls_test_argument_t;
 
 #endif /* TEST_ARGUMENTS_H */