diff --git a/episodes/30-dplyr.Rmd b/episodes/30-dplyr.Rmd
index 032138ee4..9e260261b 100644
--- a/episodes/30-dplyr.Rmd
+++ b/episodes/30-dplyr.Rmd
@@ -511,7 +511,6 @@ rna %>%
 ## 3.
 rna %>%
   filter(sample == "GSM2545336") %>%
-  group_by(gene_biotype) %>%
   count(gene_biotype) %>%
   arrange(desc(n))
 ## 4.