diff --git a/contenttype.go b/contenttype.go
index 13f244d..ef00adb 100755
--- a/contenttype.go
+++ b/contenttype.go
@@ -82,6 +82,9 @@ func SetContentTypeIfMedia(w http.ResponseWriter, r *http.Request) {
 	case ".gz":
 		w.Header().Set("Content-Encoding", "gzip")
 		v = "application/gzip"
+		if path.Ext(r.URL.Path) == ".js.gz" {
+			v = "application/javascript"
+		}
 	case ".gif":
 		v = "image/gif"
 	case ".htm,":
diff --git a/gzipresponsewriter.go b/gzipresponsewriter.go
index 05467be..6947cf0 100755
--- a/gzipresponsewriter.go
+++ b/gzipresponsewriter.go
@@ -12,6 +12,9 @@ type GZipResponseWriter struct {
 }
 
 func Can(r *http.Request) bool {
+	if strings.HasSuffix(r.URL.Path, ".gz") {
+		return false
+	}
 	encodings, _ := r.Header["Accept-Encoding"]
 	for _, encoding := range encodings {
 		items := strings.Split(encoding, ",")