diff --git a/file.c b/file.c
index e8db1069f7..f94bef04aa 100644
--- a/file.c
+++ b/file.c
@@ -4582,7 +4582,7 @@ rb_check_realpath_internal(VALUE basedir, VALUE path, rb_encoding *origenc, enum
         rb_sys_fail_path(unresolved_path);
     }
     resolved = ospath_new(resolved_ptr, strlen(resolved_ptr), rb_filesystem_encoding());
-# if defined(NEEDS_REALPATH_BUFFER) && NEEDS_REALPATH_BUFFER
+# if !(defined(NEEDS_REALPATH_BUFFER) && NEEDS_REALPATH_BUFFER)
     free(resolved_ptr);
 # endif