diff --git a/main.cc b/main.cc
index 0be0146..8046875 100644
--- a/main.cc
+++ b/main.cc
@@ -140,14 +140,16 @@ struct Grid {
     return b - x(pos);
   }
 
-  auto next_pos(Pos const &pos) const noexcept -> Pos {
-    if (const auto p = x(pos) + 1 + y(pos) * length_; p >= grid_.size()) { return std::make_pair(0, length_); } else {
+  /** Get the next position to check.  n is the size of the square we just
+   *  added.
+   */
+  auto next_pos(Pos const &pos, int n) const noexcept -> Pos {
+    const auto p = x(pos) + n + y(pos) * length_;
       const auto next_p = grid_.find('.', p);
       if (next_p == std::string::npos) {
         return std::make_pair(0, length_);
       }
       return std::make_pair(next_p % length_, next_p / length_);
-    }
   }
 
   std::string grid_;
@@ -176,7 +178,7 @@ auto find_solution_impl(Grid &grid, int n, Pos const &pos, Avail &avail_sqs) ->
     auto const sq = Square(pos, idx);
     --avail_sqs[idx];
     grid.add(sq);
-    if (find_solution_impl(grid, n, grid.next_pos(pos), avail_sqs)) { return true; }
+    if (find_solution_impl(grid, n, grid.next_pos(pos, idx), avail_sqs)) { return true; }
     ++avail_sqs[idx];
     grid.clear(sq);
   }