diff --git a/attribute/generated.go b/attribute/generated.go
index 9b5b083..7177b30 100644
--- a/attribute/generated.go
+++ b/attribute/generated.go
@@ -4,14 +4,13 @@
 package attribute
 
 import "gitlab.codemonkeysoftware.net/b/hatmill"
-import "strings"
 import "strconv"
 
 // Accept creates a "accept" attribute
 func Accept(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "accept",
-		Value: String(strings.Join(value, ",")),
+		Value: String(CommaList(value).String()),
 	}
 }
 
@@ -672,7 +671,7 @@ func Srclang(value string) hatmill.Attrib {
 func Srcset(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "srcset",
-		Value: String(strings.Join(value, ",")),
+		Value: String(CommaList(value).String()),
 	}
 }
 
diff --git a/attribute/generated_test.go b/attribute/generated_test.go
index 34b06fc..a988952 100644
--- a/attribute/generated_test.go
+++ b/attribute/generated_test.go
@@ -14,15 +14,6 @@ func testAttribValue(t *testing.T, attrib hatmill.Attrib, expectedValue string)
 	}
 }
 
-func TestCommaList(t *testing.T) {
-	t.Run("empty", func(t *testing.T) {
-		testAttribValue(t, attribute.Class(), "")
-	})
-	t.Run("nonempty", func(t *testing.T) {
-		testAttribValue(t, attribute.Accept("alpha", "bravo", "charlie"), "alpha,bravo,charlie")
-	})
-}
-
 func TestString(t *testing.T) {
 	const s = "abcdefg"
 	testAttribValue(t, attribute.Id(s), s)
diff --git a/attribute/value_types.go b/attribute/value_types.go
index 761f331..a66604f 100644
--- a/attribute/value_types.go
+++ b/attribute/value_types.go
@@ -7,3 +7,9 @@ type SpaceList []string
 func (l SpaceList) String() string {
 	return strings.Join(l, " ")
 }
+
+type CommaList []string
+
+func (l CommaList) String() string {
+	return strings.Join(l, ",")
+}
diff --git a/attribute/value_types_test.go b/attribute/value_types_test.go
index cef5d75..f5ed050 100644
--- a/attribute/value_types_test.go
+++ b/attribute/value_types_test.go
@@ -22,3 +22,15 @@ func TestSpaceList(t *testing.T) {
 		expectEqualStrings(t, actual, expected)
 	})
 }
+
+func TestCommaList(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		expectEqualStrings(t, attribute.CommaList{}.String(), "")
+	})
+
+	t.Run("nonempty", func(t *testing.T) {
+		expected := "alpha,bravo,charlie"
+		actual := attribute.CommaList{"alpha", "bravo", "charlie"}.String()
+		expectEqualStrings(t, actual, expected)
+	})
+}
diff --git a/internal/codegen/codegen.go b/internal/codegen/codegen.go
index 3db45dd..6b79ce9 100644
--- a/internal/codegen/codegen.go
+++ b/internal/codegen/codegen.go
@@ -71,8 +71,7 @@ var attribTypes = map[string]AttribTypeInfo{
 		Template: simpleTemplate("...string", "SpaceList(%s).String()"),
 	},
 	"comma list": {
-		Template: listTemplate(","),
-		Imports:  []string{"strings"},
+		Template: simpleTemplate("...string", "CommaList(%s).String()"),
 	},
 }