diff --git a/query.go b/query.go
index fe86bf0..293afeb 100644
--- a/query.go
+++ b/query.go
@@ -24,19 +24,32 @@ func (s *Selection) IsMatcher(m Matcher) bool {
 // IsFunction checks the current matched set of elements against a predicate and
 // returns true if at least one of these elements matches.
 func (s *Selection) IsFunction(f func(int, *Selection) bool) bool {
-	return s.FilterFunction(f).Length() > 0
+	for i, n := range s.Nodes {
+		if f(i, newSingleSelection(n, s.document)) {
+			return true
+		}
+	}
+	return false
 }
 
 // IsSelection checks the current matched set of elements against a Selection object
 // and returns true if at least one of these elements matches.
 func (s *Selection) IsSelection(sel *Selection) bool {
-	return s.FilterSelection(sel).Length() > 0
+	if sel == nil {
+		return false
+	}
+	return s.IsNodes(sel.Nodes...)
 }
 
 // IsNodes checks the current matched set of elements against the specified nodes
 // and returns true if at least one of these elements matches.
 func (s *Selection) IsNodes(nodes ...*html.Node) bool {
-	return s.FilterNodes(nodes...).Length() > 0
+	for _, n := range s.Nodes {
+		if isInSlice(nodes, n) {
+			return true
+		}
+	}
+	return false
 }
 
 // Contains returns true if the specified Node is within,