diff --git a/src/header/pthread/cbindgen.toml b/src/header/pthread/cbindgen.toml
index 04b8d7da80..17dd973546 100644
--- a/src/header/pthread/cbindgen.toml
+++ b/src/header/pthread/cbindgen.toml
@@ -1,3 +1,11 @@
+# POSIX header spec: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/pthread.h.html
+#
+# Spec quotations relating to includes:
+# - "The <pthread.h> header shall define the pthread_attr_t, pthread_barrier_t, pthread_barrierattr_t, pthread_cond_t, pthread_condattr_t, pthread_key_t, pthread_mutex_t, pthread_mutexattr_t, pthread_once_t, pthread_rwlock_t, pthread_rwlockattr_t, pthread_spinlock_t, and pthread_t types as described in <sys/types.h>."
+# - "Inclusion of the <pthread.h> header shall make symbols defined in the headers <sched.h> and <time.h> visible."
+#
+# bits/pthread.h bring in the types from sys/types.h
+# features.h needed for no return (Rust never type)
 sys_includes = ["sched.h", "time.h", "bits/pthread.h", "features.h"]
 include_guard = "_RELIBC_PTHREAD_H"
 language = "C"