diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index ad1bbf4fa..5682d7886 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -106,6 +106,8 @@ Upcoming Release
 
 * Adapt the disabling of transmission expansion in myopic foresight optimisations when limit is already reached to also handle cost limits.
 
+* Fix duplicated years in `add_land_use_constraint_m`.
+
 PyPSA-Eur 0.10.0 (19th February 2024)
 =====================================
 
diff --git a/scripts/solve_network.py b/scripts/solve_network.py
index 7e53e6063..7adf492a6 100644
--- a/scripts/solve_network.py
+++ b/scripts/solve_network.py
@@ -165,7 +165,7 @@ def _add_land_use_constraint_m(n, planning_horizons, config):
 
         previous_years = [
             str(y)
-            for y in planning_horizons + grouping_years
+            for y in set(planning_horizons + grouping_years)
             if y < int(snakemake.wildcards.planning_horizons)
         ]