diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index d1b7b356..c7d89c04 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -24,6 +24,8 @@ Upcoming Release
 
 * Resource definitions for memory usage now follow [Snakemake standard resource definition](https://snakemake.readthedocs.io/en/stable/snakefiles/rules.html#standard-resources) ```mem_mb`` rather than ``mem``.
 
+* Network building is made deterministic by supplying a fixed random state to network clustering routines.
+
 
 PyPSA-Eur 0.4.0 (22th September 2021)
 =====================================
diff --git a/scripts/cluster_network.py b/scripts/cluster_network.py
index 525196fc..99d428d4 100644
--- a/scripts/cluster_network.py
+++ b/scripts/cluster_network.py
@@ -226,6 +226,7 @@ def busmap_for_n_clusters(n, n_clusters, solver_name, focus_weights=None, algori
         algorithm_kwds.setdefault('n_init', 1000)
         algorithm_kwds.setdefault('max_iter', 30000)
         algorithm_kwds.setdefault('tol', 1e-6)
+        algorithm_kwds.setdefault('random_state', 0)
 
     n.determine_network_topology()