diff --git a/examples/collection-functions/collection-functions.go b/examples/collection-functions/collection-functions.go
index 636cba8..b242241 100644
--- a/examples/collection-functions/collection-functions.go
+++ b/examples/collection-functions/collection-functions.go
@@ -36,7 +36,7 @@ func All(elems []string, f func(string) bool) bool {
 
 func Filter(vs []string, f func(string) bool) []string {
     vsf := make([]string, 0)
-    for _, v := range elems {
+    for _, v := range vs {
         if f(v) {
             vsf = append(vsf, v)
         }