diff --git a/tests/include/test/macros.h b/tests/include/test/macros.h
index aaf13ad..21552e7 100644
--- a/tests/include/test/macros.h
+++ b/tests/include/test/macros.h
@@ -75,7 +75,7 @@
 /* A compile-time constant with the value 0. If `const_expr` is not a
  * compile-time constant with a nonzero value, cause a compile-time error. */
 #define STATIC_ASSERT_EXPR( const_expr )                                \
-    ( 0 && sizeof( struct { int STATIC_ASSERT : 1 - 2 * ! ( const_expr ); } ) )
+    ( 0 && sizeof( struct { unsigned int STATIC_ASSERT : 1 - 2 * ! ( const_expr ); } ) )
 /* Return the scalar value `value` (possibly promoted). This is a compile-time
  * constant if `value` is. `condition` must be a compile-time constant.
  * If `condition` is false, arrange to cause a compile-time error. */