diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index 69564ac6..c860f030 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -1,8 +1,10 @@
 Release Notes
 =============
 
-.. Upcoming Version
-.. ----------------
+Upcoming Version
+----------------
+
+* Fix the `slice_size` argument in the `solve` function. The argument was not properly passed to the `to_file` function.
 
 Version 0.4.0
 --------------
diff --git a/linopy/model.py b/linopy/model.py
index 160a16e3..bb9b41ee 100644
--- a/linopy/model.py
+++ b/linopy/model.py
@@ -1124,7 +1124,9 @@ def solve(
                     env=env,
                 )
             else:
-                problem_fn = self.to_file(to_path(problem_fn), io_api)
+                problem_fn = self.to_file(
+                    to_path(problem_fn), io_api, slice_size=slice_size
+                )
                 result = solver.solve_problem_from_file(
                     problem_fn=to_path(problem_fn),
                     solution_fn=to_path(solution_fn),