diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index 2d2eae23..70927880 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -14,6 +14,8 @@ Upcoming Release
 
 * Fix EQ constraint for the case no hydro inflow is available
 
+* Bugfix in the reserve constraint will increase demand related reserve requirements
+
 PyPSA-Eur 0.6.1 (20th September 2022)
 =====================================
 
diff --git a/scripts/solve_network.py b/scripts/solve_network.py
index 575cd078..3acc384a 100755
--- a/scripts/solve_network.py
+++ b/scripts/solve_network.py
@@ -281,7 +281,7 @@ def add_operational_reserve_margin_constraint(n, config):
         ).sum(1)
 
     # Total demand at t
-    demand = n.loads_t.p.sum(1)
+    demand = n.loads_t.p_set.sum(1)
 
     # VRES potential of non extendable generators
     capacity_factor = n.generators_t.p_max_pu[vres_i.difference(ext_i)]