diff --git a/bluecellulab/graph.py b/bluecellulab/graph.py
index a65cfc66..7afd0502 100644
--- a/bluecellulab/graph.py
+++ b/bluecellulab/graph.py
@@ -42,7 +42,7 @@ def plot_graph(G: nx.Graph, node_size: float = 400, edge_width: float = 0.4, nod
     populations = list(set([cell_id.population_name for cell_id in G.nodes()]))
 
     # Create a color map for each population
-    color_map = plt.cm.tab20(np.linspace(0, 1, len(populations)))
+    color_map = plt.cm.tab20(np.linspace(0, 1, len(populations)))  # type: ignore[attr-defined]
     population_color = dict(zip(populations, color_map))
 
     # Create node colors based on their population
@@ -50,7 +50,7 @@ def plot_graph(G: nx.Graph, node_size: float = 400, edge_width: float = 0.4, nod
 
     # Extract weights for edge color mapping
     edge_weights = [d['weight'] for _, _, d in G.edges(data=True)]
-    edge_colors = plt.cm.Greens(np.interp(edge_weights, (min(edge_weights), max(edge_weights)), (0.3, 1)))
+    edge_colors = plt.cm.Greens(np.interp(edge_weights, (min(edge_weights), max(edge_weights)), (0.3, 1)))  # type: ignore[attr-defined]
 
     # Create positions using spring layout for the entire graph
     pos = nx.spring_layout(G, k=node_distance)