diff --git a/gc.c b/gc.c
index c6502dbd..d2b04818 100644
--- a/gc.c
+++ b/gc.c
@@ -273,6 +273,11 @@ void gc_remove_mutator(gc_thread_data * thd)
   pthread_mutex_unlock(&mutators_lock);
 }
 
+/**
+ * @brief Determine if the given mutator is in the list of active threads.
+ * @param thd Thread data object of the m
+ * @return A true value if the mutator is active, 0 otherwise.
+ */
 int gc_is_mutator_active(gc_thread_data *thd)
 {
   ck_array_iterator_t iterator;
diff --git a/runtime.c b/runtime.c
index 3d352c8d..70d44539 100644
--- a/runtime.c
+++ b/runtime.c
@@ -5161,6 +5161,9 @@ void Cyc_start_trampoline(gc_thread_data * thd)
   exit(1);
 }
 
+/**
+ * @brief A helper function for calling `gc_mark_globals`.
+ */
 void gc_request_mark_globals(void)
 {
   gc_mark_globals(Cyc_global_variables, global_table);