diff --git a/linopy/solvers.py b/linopy/solvers.py
index 70ace0ce..987c7b70 100644
--- a/linopy/solvers.py
+++ b/linopy/solvers.py
@@ -294,7 +294,7 @@ def __getattr__(self, attr: str) -> Any:
 
 
 gurobipy = _LazyModule("gurobipy")  # type: ignore[assignment]
-highspy = _LazyModule("highspy")
+highspy = _LazyModule("highspy")  # type: ignore[assignment]
 scip = _LazyModule("pyscipopt")
 cplex = _LazyModule("cplex")
 knitro = _LazyModule("knitro")
@@ -1656,7 +1656,7 @@ def _build_solver_model(
             int_mask = (vtypes == "B") | (vtypes == "I") | (vtypes == "S")
             labels = np.arange(len(vtypes))[int_mask]
             integrality = np.array(
-                [integrality_map[v] for v in vtypes[int_mask]], dtype=np.int32
+                [integrality_map[v] for v in vtypes[int_mask]], dtype=np.uint8
             )
             h.changeColsIntegrality(len(labels), labels, integrality)