diff --git a/src/ruby/ext/grpc/rb_signal.c b/src/ruby/ext/grpc/rb_signal.c
index dd60b0f251f694d1a5fe2b3fab772e0367ec2233..a9e512374ba4639f5a7ee2476913d2dd99279434 100644
--- a/src/ruby/ext/grpc/rb_signal.c
+++ b/src/ruby/ext/grpc/rb_signal.c
@@ -44,6 +44,10 @@ static void (*old_sigterm_handler)(int);
 
 static volatile bool signal_received = false;
 
+/* This has to be handled at the C level instead of Ruby, because Ruby signal
+ * handlers are constrained to run in the main interpreter thread. If that main
+ * thread is blocked on grpc_completion_queue_pluck, the signal handlers will
+ * never run */
 static void handle_signal(int signum) {
   signal_received = true;
   if (signum == SIGINT) {