diff --git a/provider/assume-role/assume-role.go b/provider/assume-role/assume-role.go
index 64bb26a..e11553f 100644
--- a/provider/assume-role/assume-role.go
+++ b/provider/assume-role/assume-role.go
@@ -176,7 +176,7 @@ func (h *Handler) handle(ctx context.Context, req *requestBody) (*responseBody,
 }
 
 func (h *Handler) handleError(w http.ResponseWriter, r *http.Request, err error) {
-	log.Println(err)
+	log.Printf("error: %v", err)
 	status := http.StatusInternalServerError
 	var body *errorResponseBody
 
diff --git a/provider/assume-role/github/github.go b/provider/assume-role/github/github.go
index f5465c2..b8b4d27 100644
--- a/provider/assume-role/github/github.go
+++ b/provider/assume-role/github/github.go
@@ -118,7 +118,7 @@ func canonicalURL(rawurl string) (string, error) {
 	case "":
 		u.Scheme = "http"
 	default:
-		return "", fmt.Errorf("unknown scheme: %s", u.Scheme)
+		return "", fmt.Errorf("unknown scheme: %q", u.Scheme)
 	}
 	if port == defaultPort {
 		port = ""