diff --git a/R/plugins.R b/R/plugins.R
index a321490..9a190c3 100644
--- a/R/plugins.R
+++ b/R/plugins.R
@@ -40,7 +40,7 @@ tau_tooltip <- function(tau, fields = NULL) {
 #'   tau_legend()
 tau_legend <- function(tau) {
 
-  if ((!is.null(tau$x$color)) & (!is.null(tau$x$size))) {
+  if (is.null(tau$x$color) & is.null(tau$x$size)) {
     message("Neither color nor size aesthetics have been mapped. Legend plugin will be active but not displayed.")
   }