diff --git a/src/graph/graph.hh b/src/graph/graph.hh
index 372f05e5b..dc5b6a36f 100644
--- a/src/graph/graph.hh
+++ b/src/graph/graph.hh
@@ -1187,6 +1187,11 @@ struct graph_t
       }
     }
 
+    for (unsigned i = 0; i < vertices_.length; i++)
+      // parents arrays must be accurate or downstream operations like cycle detection
+      // and sorting won't work correctly.
+      check_success (!vertices_[i].parents.in_error ());
+
     parents_invalid = false;
   }
 
diff --git a/src/hb-repacker.hh b/src/hb-repacker.hh
index 6817ffae4..7a3143cec 100644
--- a/src/hb-repacker.hh
+++ b/src/hb-repacker.hh
@@ -393,6 +393,14 @@ hb_resolve_overflows (const T& packed,
     return nullptr;
   }
 
+  if (sorted_graph.in_error ())
+  {
+    // Allocations failed somewhere
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "Graph is in error, likely due to a memory allocation error.");
+    return nullptr;
+  }
+
   if (!hb_resolve_graph_overflows (table_tag, max_rounds, recalculate_extensions, sorted_graph))
     return nullptr;
 
diff --git a/test/fuzzing/graphs/clusterfuzz-testcase-minimized-hb-repacker-fuzzer-6014493291577344 b/test/fuzzing/graphs/clusterfuzz-testcase-minimized-hb-repacker-fuzzer-6014493291577344
new file mode 100644
index 000000000..a29d1e2fb
Binary files /dev/null and b/test/fuzzing/graphs/clusterfuzz-testcase-minimized-hb-repacker-fuzzer-6014493291577344 differ