diff --git a/src/ssb.c b/src/ssb.c
index 7f9e851d..1362780a 100644
--- a/src/ssb.c
+++ b/src/ssb.c
@@ -3760,7 +3760,12 @@ void tf_ssb_ref(tf_ssb_t* ssb)
 
 void tf_ssb_unref(tf_ssb_t* ssb)
 {
-	ssb->ref_count--;
+	int new_count = --ssb->ref_count;
+	if (new_count < 0)
+	{
+		tf_printf("tf_ssb_unref past 0: %d\n", new_count);
+		abort();
+	}
 }
 
 void tf_ssb_set_main_thread(tf_ssb_t* ssb, bool main_thread)