diff --git a/README.md b/README.md
index 352b6789d284..4266d376e1ed 100644
--- a/README.md
+++ b/README.md
@@ -291,6 +291,7 @@ sudo apt install \
   bazel \
   clang \
   libc++-dev \
+  libc++abi-dev \
   lld
 
 # Download Carbon's code.