diff --git a/skfeature/function/similarity_based/lap_score.py b/skfeature/function/similarity_based/lap_score.py
index 5bee2f8..d9e4340 100644
--- a/skfeature/function/similarity_based/lap_score.py
+++ b/skfeature/function/similarity_based/lap_score.py
@@ -32,8 +32,9 @@ def lap_score(X, **kwargs):
     # if 'W' is not specified, use the default W
     if 'W' not in kwargs.keys():
         W = construct_W(X)
-    # construct the affinity matrix W
-    W = kwargs['W']
+    else:
+        # construct the affinity matrix W
+        W = kwargs['W']
     # build the diagonal D matrix from affinity matrix W
     D = np.array(W.sum(axis=1))
     L = W