diff --git a/book/src/language-tour/check.md b/book/src/language-tour/check.md
index d7ef5bab..20158bbb 100644
--- a/book/src/language-tour/check.md
+++ b/book/src/language-tour/check.md
@@ -1 +1,8 @@
 # Check
+
+Check is faster than assert but has weaker guarantees.
+You can unpack (1-match) data in a check.
+
+```gleam
+check Some(x) = Option(Int)
+```
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