diff --git a/DESCRIPTION b/DESCRIPTION
index 58af8d5..fa4f0ad 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: flipPlots
 Type: Package
 Title: Creates Plots
-Version: 1.3.8
+Version: 1.3.9
 Author: Displayr <opensource@displayr.com>
 Maintainer: Displayr <opensource@displayr.com>
 Description: Wrappers for various plot types.
diff --git a/R/sankeydiagram.R b/R/sankeydiagram.R
index b9e37f2..bc5fceb 100644
--- a/R/sankeydiagram.R
+++ b/R/sankeydiagram.R
@@ -176,7 +176,7 @@ SankeyDiagram <- function(data = NULL, links.and.nodes = NULL, output.data.only
 
 getNodeGroups <- function(type, links)
 {
-    num.nodes <- length(unique(unlist(links$source, links$target)))
+    num.nodes <- length(unique(c(unlist(links$source), unlist(links$target))))
     grps <- rep(NA, num.nodes)
     gval <- rep(NA, num.nodes)
 
diff --git a/tests/testthat/test-sankeydiagram.R b/tests/testthat/test-sankeydiagram.R
index 1ef2501..18d4ffe 100644
--- a/tests/testthat/test-sankeydiagram.R
+++ b/tests/testthat/test-sankeydiagram.R
@@ -1099,6 +1099,7 @@ datText <- structure(list(Q1_Gender = structure(c(2L, 2L, 1L, 1L, 2L, 2L,
 test_that("Many categories",
 {
     expect_error(SankeyDiagram(datText), NA)
+    expect_error(SankeyDiagram(datText, link.color = "Last variable"), NA)
 })
 
 dat.longnames <- structure(list(`D3 - Gender` = structure(c(2L, 1L, 2L, 2L, 2L,