diff --git a/examples/cluster/plot_dbscan.py b/examples/cluster/plot_dbscan.py
index b5a9bfafc066995453efc5d8bd4ddaddcb57fbeb..a12b3d39128b6f71a1aeac2071bbf0fe885299cf 100644
--- a/examples/cluster/plot_dbscan.py
+++ b/examples/cluster/plot_dbscan.py
@@ -57,16 +57,16 @@ colors = [plt.cm.Spectral(each)
 for k, col in zip(unique_labels, colors):
     if k == -1:
         # Black used for noise.
-        col = 'k'
+        col = [0, 0, 0, 1]
 
     class_member_mask = (labels == k)
 
     xy = X[class_member_mask & core_samples_mask]
-    plt.plot(xy[:, 0], xy[:, 1], 'o', markerfacecolor=col,
+    plt.plot(xy[:, 0], xy[:, 1], 'o', markerfacecolor=tuple(col),
              markeredgecolor='k', markersize=14)
 
     xy = X[class_member_mask & ~core_samples_mask]
-    plt.plot(xy[:, 0], xy[:, 1], 'o', markerfacecolor=col,
+    plt.plot(xy[:, 0], xy[:, 1], 'o', markerfacecolor=tuple(col),
              markeredgecolor='k', markersize=6)
 
 plt.title('Estimated number of clusters: %d' % n_clusters_)