diff --git a/src/items/functions.md b/src/items/functions.md
index 7572ba331c7df..6ecc3173ab99c 100644
--- a/src/items/functions.md
+++ b/src/items/functions.md
@@ -165,3 +165,4 @@ same type as the functions declared in an extern block.
 let fptr: extern "C" fn() -> i32 = new_i32;
 ```
 
+As non-Rust calling conventions do not support unwinding, unwinding past the end of an extern function will cause the process to abort (in LLVM, this is implemented by executing an illegal instruction).