diff --git a/numbers.Rmd b/numbers.Rmd
index db9ee29..af93d01 100644
--- a/numbers.Rmd
+++ b/numbers.Rmd
@@ -344,7 +344,7 @@ slide_vec(x, sum, .before = 2, .after = 2, .complete = TRUE)
 
 These are often used with numbers, but can be applied to most other column types.
 
-### Missing values
+### Missing values {#missing-values-numbers}
 
 `coalesce()`