diff --git a/cmd/smweb/main.go b/cmd/smweb/main.go
index e97095b..f483486 100644
--- a/cmd/smweb/main.go
+++ b/cmd/smweb/main.go
@@ -6,22 +6,15 @@ import (
 	"os"
 	"strconv"
 
-	"github.com/elazarl/go-bindata-assetfs"
 	"mcquay.me/web"
 )
 
 func main() {
-	var fs http.FileSystem
-	if os.Getenv("SM_DEV") == "" {
-		fs = &assetfs.AssetFS{
-			Asset:     web.Asset,
-			AssetDir:  web.AssetDir,
-			AssetInfo: web.AssetInfo,
-			Prefix:    "static",
-		}
-	} else {
-		fs = http.Dir(os.Getenv("SM_STATIC"))
+	static := ""
+	if s := os.Getenv("STATIC"); s != "" {
+		static = s
 	}
+
 	port := 8000
 	if os.Getenv("PORT") != "" {
 		p, err := strconv.Atoi(os.Getenv("PORT"))
@@ -31,13 +24,11 @@ func main() {
 		}
 		port = p
 	}
-	// XXX: beware: I've copy/pasted this twice now and been confused because
-	// I ought to have been using my own servemux
-	http.Handle(
-		"/",
-		http.FileServer(fs),
-	)
-	if err := http.ListenAndServe(fmt.Sprintf(":%d", port), nil); err != nil {
+
+	sm := http.NewServeMux()
+
+	web.NewServer(sm, static)
+	if err := http.ListenAndServe(fmt.Sprintf(":%d", port), sm); err != nil {
 		fmt.Fprintf(os.Stderr, "problem serving: %v\n", err)
 		os.Exit(1)
 	}
diff --git a/web.go b/web.go
index 1fee15d..6fcd4d9 100644
--- a/web.go
+++ b/web.go
@@ -1,6 +1,34 @@
 package web
 
+import (
+	"net/http"
+	"path/filepath"
+
+	assetfs "github.com/elazarl/go-bindata-assetfs"
+)
+
 //go:generate go get github.com/jteeuwen/go-bindata/...
 //go:generate go get github.com/elazarl/go-bindata-assetfs/...
 //go:generate rm -f static.go
 //go:generate go-bindata -o static.go -pkg=web static/...
+
+func NewServer(sm *http.ServeMux, static string) {
+	var fs http.FileSystem
+	if p, d := filepath.Split(static); d == "static" {
+		static = p
+	}
+	fs = http.Dir(static)
+	if static == "" {
+		fs = &assetfs.AssetFS{
+			Asset:     Asset,
+			AssetDir:  AssetDir,
+			AssetInfo: AssetInfo,
+			Prefix:    "static",
+		}
+	}
+
+	sm.Handle(
+		"/",
+		http.FileServer(fs),
+	)
+}