diff --git a/http/handler.go b/http/handler.go
index 3a32332..8293b35 100644
--- a/http/handler.go
+++ b/http/handler.go
@@ -11,11 +11,18 @@ import "path/filepath"
 import "git.tebibyte.media/sashakoshka/step"
 import "git.tebibyte.media/sashakoshka/goutil/container"
 
+type ErrorData struct {
+	Status  int
+	Message any
+}
+
 type Handler struct {
 	Environment *step.Environment
 	Directories bool
 	StepExt     ucontainer.Set[string]
 	Index       []string
+	ErrorDocument     string
+	DirectoryDocument string
 }
 
 func (this *Handler) ServeHTTP (res http.ResponseWriter, req *http.Request) {
@@ -39,9 +46,7 @@ func (this *Handler) ServeHTTP (res http.ResponseWriter, req *http.Request) {
 
 	info, err := statFile(filesystem, pathToName(pat))
 	if err != nil {
-		// TODO need more detailed error, should allow specifying error
-		// documents
-		this.serveError(res, req, http.StatusNotFound, req.URL)
+		this.serveError(res, req, http.StatusNotFound, req.URL, false)
 		return
 	}
 	if info.IsDir() {
@@ -57,12 +62,12 @@ func (this *Handler) ServeHTTP (res http.ResponseWriter, req *http.Request) {
 			info, err := statFile(filesystem, pathToName(currentPath))
 			if err != nil   { continue }
 			if info.IsDir() { continue }
-			this.serveFile(res, req, filesystem, currentPath)
+			this.serveFile(res, req, currentPath)
 			return
 		}
 
 		if !this.Directories {
-			this.serveError(res, req, http.StatusForbidden, req.URL)
+			this.serveError(res, req, http.StatusForbidden, req.URL, false)
 			return
 		}
 
@@ -72,21 +77,32 @@ func (this *Handler) ServeHTTP (res http.ResponseWriter, req *http.Request) {
 		// as data
 	}
 
-	this.serveFile(res, req, filesystem, pat)
+	this.serveFile(res, req, pat)
 }
 
-func (this *Handler) serveFile (res http.ResponseWriter, req *http.Request, filesystem fs.FS, pat string) {
+func (this *Handler) serveFile (
+	res http.ResponseWriter,
+	req *http.Request,
+	pat string,
+) {
 	name := pathToName(pat)
 	if !this.StepExt.Has(filepath.Ext(name)) {
 		// just a normal file
 		http.ServeFileFS(res, req, this.Environment.GetFS(), name)
 		return
 	}
+	this.serveDocument(res, req, name)	
+}
 
+func (this *Handler) serveDocument (
+	res http.ResponseWriter,
+	req *http.Request,
+	name string,
+) {
 	// parse
 	document, err := this.Environment.Parse(name)
 	if err != nil {
-		this.serveError(res, req, http.StatusInternalServerError, err)
+		this.serveError(res, req, http.StatusInternalServerError, err, false)
 		return
 	}
 
@@ -115,7 +131,7 @@ func (this *Handler) serveFile (res http.ResponseWriter, req *http.Request, file
 		Data: data,
 	})
 	if err != nil {
-		this.serveError(res, req, http.StatusInternalServerError, err)
+		this.serveError(res, req, http.StatusInternalServerError, err, false)
 		return
 	}
 
@@ -126,16 +142,41 @@ func (this *Handler) serveFile (res http.ResponseWriter, req *http.Request, file
 	}
 }
 
-func (this *Handler) serveError (res http.ResponseWriter, req *http.Request, status int, message any) {
-	res.Header().Add("Content-Type", "text/plain")
-	res.WriteHeader(status)
-	// TODO: allow customization with templates
-	if message == nil {
-		fmt.Fprintf(res, "%d %s\n", status, http.StatusText(status))
-	} else {
-		fmt.Fprintf(res, "%d %s: %v\n", status, http.StatusText(status), message)
-	}
+func (this *Handler) serveError (
+	res http.ResponseWriter,
+	req *http.Request,
+	status int,
+	message any,
+	safeMode bool,
+) {
 	log.Printf("ERR %d %s: %v\n", status, http.StatusText(status), message)
+	if safeMode || this.ErrorDocument == "" {
+		res.Header().Add("Content-Type", "text/plain")
+		res.WriteHeader(status)
+		// TODO: allow customization with templates
+		if message == nil {
+			fmt.Fprintf(res, "%d %s\n", status, http.StatusText(status))
+		} else {
+			fmt.Fprintf(res, "%d %s: %v\n", status, http.StatusText(status), message)
+		}
+		return
+	}
+
+	document, err := this.Environment.Parse(this.ErrorDocument)
+	if err != nil {
+		this.serveError(res, req, http.StatusInternalServerError, err, true)
+		return
+	}
+	err = document.Execute(res, step.ExecutionData {
+		Data: ErrorData {
+			Status:  status,
+			Message: message,
+		},
+	})
+	if err != nil {
+		this.serveError(res, req, http.StatusInternalServerError, err, true)
+		return
+	}
 }
 
 func (this *Handler) logErr (name string, err error) {