diff --git a/R/variablesChartsSubgroups.R b/R/variablesChartsSubgroups.R
index 97862a97..b60792e2 100644
--- a/R/variablesChartsSubgroups.R
+++ b/R/variablesChartsSubgroups.R
@@ -148,7 +148,7 @@ variablesChartsSubgroups <- function(jaspResults, dataset, options) {
   }
 
   # Check if all subgroups are of size 1 and return error if yes
-  if (all(apply(dataset[measurements], 1, function(x) sum(!is.na(x))) == 1)) {
+  if (all(apply(dataset[measurements], 1, function(x) sum(!is.na(x))) <= 1)) {
     plot <- createJaspPlot(title = gettext("Control charts"), width = 700, height = 400)
     plot$setError(gettext("All subgroups are of size 1. Variables charts for subgroups cannot be calculated. Use variables charts for individuals."))
     jaspResults[["plot"]] <- plot