diff --git a/src/corelib/itemmodels/qgenericitemmodel.h b/src/corelib/itemmodels/qgenericitemmodel.h
index cd4bae6342a..9cce06cba64 100644
--- a/src/corelib/itemmodels/qgenericitemmodel.h
+++ b/src/corelib/itemmodels/qgenericitemmodel.h
@@ -1301,7 +1301,10 @@ protected:
     int columnCount(const QModelIndex &) const
     {
         // all levels of a tree have to have the same, static, column count
-        return Base::static_column_count;
+        if constexpr (Base::one_dimensional_range)
+            return 1;
+        else
+            return Base::static_column_count; // if static_column_count is -1, static assert fires
     }
 
     static constexpr Qt::ItemFlags defaultFlags()