diff --git a/html/node.go b/html/node.go
index 2c1cade..633ee15 100644
--- a/html/node.go
+++ b/html/node.go
@@ -177,7 +177,7 @@
 // contains returns whether a is within s.
 func (s *nodeStack) contains(a atom.Atom) bool {
 	for _, n := range *s {
-		if n.DataAtom == a {
+		if n.DataAtom == a && n.Namespace == "" {
 			return true
 		}
 	}
diff --git a/html/testdata/go/template.dat b/html/testdata/go/template.dat
index 98481b9..ceaf022 100644
--- a/html/testdata/go/template.dat
+++ b/html/testdata/go/template.dat
@@ -35,3 +35,28 @@
 |         <math mo>
 |           <template>
 |             content
+
+#data
+<svg><template><desc><t><svg></template>
+#errors
+#document
+| <html>
+|   <head>
+|   <body>
+|     <svg svg>
+|       <svg template>
+|         <svg desc>
+|           <t>
+|             <svg svg>
+
+#data
+<math><template><mn><b></template>
+#errors
+#document
+| <html>
+|   <head>
+|   <body>
+|     <math math>
+|       <math template>
+|         <math mn>
+|           <b>