1 files changed, 5 insertions, 3 deletions

diff --git a/cpp/nissy.cpp b/cpp/nissy.cpp
index e3193e1..6e1b700 100644
--- a/cpp/nissy.cpp
+++ b/cpp/nissy.cpp
@@ -166,11 +166,13 @@ namespace nissy {
                 ifs.read(reinterpret_cast<char *>(data.data()), size);
         }
 
-        error solver::check_data() const
+        error solver::check_data()
         {
-                auto err = nissy_checkdata(data.size(),
+                auto err_value = nissy_checkdata(data.size(),
                     reinterpret_cast<const char *>(data.data()));
-                return error{err};
+                error err{err_value};
+                data_checked = err.ok();
+                return err;
         }
 
         void solver::unload_data()