diff --git a/formatters/api.go b/formatters/api.go
index 9818abc..8710040 100644
--- a/formatters/api.go
+++ b/formatters/api.go
@@ -2,6 +2,7 @@ package formatters
 
 import (
 	"io"
+	"sort"
 
 	"github.com/alecthomas/chroma"
 	"github.com/alecthomas/chroma/formatters/html"
@@ -28,6 +29,7 @@ func Names() []string {
 	for name := range Registry {
 		out = append(out, name)
 	}
+	sort.Strings(out)
 	return out
 }
 
diff --git a/styles/api.go b/styles/api.go
index d0f5a61..f3ce673 100644
--- a/styles/api.go
+++ b/styles/api.go
@@ -1,6 +1,10 @@
 package styles
 
-import "github.com/alecthomas/chroma"
+import (
+	"sort"
+
+	"github.com/alecthomas/chroma"
+)
 
 // Registry of Styles.
 var Registry = map[string]*chroma.Style{}
@@ -20,6 +24,7 @@ func Names() []string {
 	for name := range Registry {
 		out = append(out, name)
 	}
+	sort.Strings(out)
 	return out
 }