diff --git a/modules/river-generator.js b/modules/river-generator.js
index bef47df6..20ee34ba 100644
--- a/modules/river-generator.js
+++ b/modules/river-generator.js
@@ -253,6 +253,7 @@
 
   const specify = function() {
     if (!pack.rivers.length) return;
+    Math.seedrandom(seed);
     const smallLength = pack.rivers.map(r => r.length||0).sort((a,b) => a-b)[Math.ceil(pack.rivers.length * .15)];
     const smallType = {"Creek":9, "River":3, "Brook":3, "Stream":1}; // weighted small river types