diff --git a/base-R.qmd b/base-R.qmd
index c4a93b3..63ccee2 100644
--- a/base-R.qmd
+++ b/base-R.qmd
@@ -41,7 +41,7 @@ We'll then help you cement that knowledge by showing how various dplyr verbs are
 
 There are five main types of things that you can subset a vector with, i.e. that can be the `i` in `x[i]`:
 
-1.  **An vector of positive integers**.
+1.  **A vector of positive integers**.
     Subsetting with positive integers keeps the elements at those positions:
 
     ```{r}