diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/NeighborRankTraverser.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/NeighborRankTraverser.java
index f9060cb692..68fd791863 100644
--- a/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/NeighborRankTraverser.java
+++ b/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/NeighborRankTraverser.java
@@ -244,7 +244,8 @@ public static class Step {
         public Step(HugeGraph g, Directions direction, List<String> labels,
                     long degree, long skipDegree, int top, int capacity) {
             E.checkArgument(top > 0 && top <= MAX_TOP,
-                            "The top of each layer can't exceed %s", MAX_TOP);
+                            "The top of each layer must be in (0, %s]",
+                            MAX_TOP);
             E.checkArgument(capacity > 0,
                             "The capacity of each layer must be > 0, " +
                             "but got %s", capacity);
diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/SingleSourceShortestPathTraverser.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/SingleSourceShortestPathTraverser.java
index cbe69c9ca5..e85f995bcd 100644
--- a/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/SingleSourceShortestPathTraverser.java
+++ b/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/SingleSourceShortestPathTraverser.java
@@ -212,11 +212,19 @@ private double edgeWeight(HugeEdge edge) {
                 !edge.property(this.weight).isPresent()) {
                 edgeWeight = 1.0;
             } else {
-                edgeWeight = edge.value(this.weight);
+                edgeWeight = this.toDouble(edge.value(this.weight));
             }
             return edgeWeight;
         }
 
+        private double toDouble(Object obj) {
+            if (obj instanceof Number) {
+                return ((Number) obj).doubleValue();
+            }
+
+            return (double) obj;
+        }
+
         private Iterator<Edge> skipSuperNodeIfNeeded(Iterator<Edge> edges) {
             if (this.skipDegree <= 0L) {
                 return edges;