diff --git a/netmap/netmap.go b/netmap/netmap.go
index b119f07..a583455 100644
--- a/netmap/netmap.go
+++ b/netmap/netmap.go
@@ -139,20 +139,12 @@ func (n nodes) appendWeightsTo(wf weightFunc, w []float64) []float64 {
 	return w
 }
 
-func flattenNodes(ns []nodes) nodes {
-	var sz, i int
-
-	for i = range ns {
-		sz += len(ns[i])
-	}
-
-	result := make(nodes, 0, sz)
-
+// flattenNodes flattens ns nested list and appends the result to the target slice.
+func flattenNodes(target nodes, ns []nodes) nodes {
 	for i := range ns {
-		result = append(result, ns[i]...)
+		target = append(target, ns[i]...)
 	}
-
-	return result
+	return target
 }
 
 // PlacementVectors sorts container nodes returned by ContainerNodes method
@@ -287,7 +279,7 @@ func (m NetMap) ContainerNodes(p PlacementPolicy, pivot []byte) ([][]NodeInfo, e
 				return nil, err
 			}
 
-			result[i] = append(result[i], flattenNodes(nodes)...)
+			result[i] = flattenNodes(result[i], nodes)
 
 			if unique {
 				c.addUsedNodes(result[i]...)
@@ -304,14 +296,14 @@ func (m NetMap) ContainerNodes(p PlacementPolicy, pivot []byte) ([][]NodeInfo, e
 			if err != nil {
 				return nil, err
 			}
-			result[i] = append(result[i], flattenNodes(nodes)...)
+			result[i] = flattenNodes(result[i], nodes)
 			c.addUsedNodes(result[i]...)
 		} else {
 			nodes, ok := c.selections[sName]
 			if !ok {
 				return nil, fmt.Errorf("selector not found: REPLICA '%s'", sName)
 			}
-			result[i] = append(result[i], flattenNodes(nodes)...)
+			result[i] = flattenNodes(result[i], nodes)
 		}
 	}
 
diff --git a/netmap/selector_test.go b/netmap/selector_test.go
index ae996dd..a4ca774 100644
--- a/netmap/selector_test.go
+++ b/netmap/selector_test.go
@@ -191,7 +191,7 @@ func TestPlacementPolicy_DeterministicOrder(t *testing.T) {
 			nss[i] = v[i]
 		}
 
-		ns := flattenNodes(nss)
+		ns := flattenNodes(nil, nss)
 		require.Equal(t, 2, len(ns))
 		return ns[0].Hash(), ns[1].Hash()
 	}