--- a/mozglue/misc/PlatformConditionVariable.h
+++ b/mozglue/misc/PlatformConditionVariable.h
@@ -31,18 +31,22 @@ class ConditionVariableImpl {
   MFBT_API ~ConditionVariableImpl();
 
   // Wake one thread that is waiting on this condition.
   MFBT_API void notify_one();
 
   // Wake all threads that are waiting on this condition.
   MFBT_API void notify_all();
 
-  // Block the current thread of execution until this condition variable is
-  // woken from another thread via notify_one or notify_all.
+  // Atomically release |lock| and sleep the current thread of execution on
+  // this condition variable.
+  // |lock| will be re-acquired before this function returns.
+  // The thread may be woken from sleep from another thread via notify_one()
+  // or notify_all(), but may also wake spuriously.  The caller should recheck
+  // its predicate after this function returns, typically in a while loop.
   MFBT_API void wait(MutexImpl& lock);
 
   MFBT_API CVStatus wait_for(MutexImpl& lock,
                              const mozilla::TimeDuration& rel_time);
 
  private:
   ConditionVariableImpl(const ConditionVariableImpl&) = delete;
   ConditionVariableImpl& operator=(const ConditionVariableImpl&) = delete;