diff --git a/README.md b/README.md
index f6f4c288a07..ad4daa47cc6 100644
--- a/README.md
+++ b/README.md
@@ -85,6 +85,14 @@ bazel build -c opt //src/workerd/server:workerd
 
 The compiled binary will be located at `bazel-bin/src/workerd/server/workerd`.
 
+If you run a Bazel build before you've installed some dependencies (like clang or libc++), and then you install the dependencies, you must clean Bazel's cache, otherwise you might get strange errors:
+
+```
+bazel clean --expunge
+```
+
+The cache will now be cleaned and you can try building again.
+
 ### Configuring `workerd`
 
 `workerd` is configured using a config file written in Cap'n Proto text format.