diff --git a/util/ng_corpus_generator.cpp b/util/ng_corpus_generator.cpp
index cb195eaf..69e7c4ef 100644
--- a/util/ng_corpus_generator.cpp
+++ b/util/ng_corpus_generator.cpp
@@ -185,7 +185,7 @@ void findPaths(const NGHolder &g, CorpusProperties &cProps,
                 continue;
             }
 
-            if (!contains(one_way_in, v) &&
+            if (p && !contains(one_way_in, v) &&
                 has_greater_than(p->begin(), p->end(), v, cycleLimit)) {
                 // Note that vertices that only have one predecessor don't need
                 // their cycle limit checked, as their predecessors will have