diff --git a/portreasons.cc b/portreasons.cc
index a841ad6c4..f4782ae6b 100644
--- a/portreasons.cc
+++ b/portreasons.cc
@@ -214,7 +214,9 @@ static state_reason_summary_t *reason_sort(state_reason_summary_t *list) {
           }
           p = q;
        }
-	   tail->next = NULL;
+      if (!tail)
+        return NULL;
+      tail->next = NULL;
       if (nmerges <= 1)  
         return list;
       insize *= 2;