diff --git a/src/core/graph.ts b/src/core/graph.ts
index db2190e14..3a3a72ae2 100644
--- a/src/core/graph.ts
+++ b/src/core/graph.ts
@@ -397,7 +397,9 @@ export class SortablePrecedenceGraph<
       } else {
         // Look further upstream for start nodes that match the type.
         for (const newStartNode of pg.getDownstreamNeighbors(node)) {
-          startNodes.add(newStartNode);
+          if (!visited.has(newStartNode)) {
+            startNodes.add(newStartNode);
+          }
         }
       }
     }