diff --git a/js/kspace.js b/js/kspace.js
index <HASH>..<HASH> 100644
--- a/js/kspace.js
+++ b/js/kspace.js
@@ -112,6 +112,10 @@ function filterFeatures(features, min, max) {
 }
 
 KnownSpace.prototype.invalidate = function(tier) {
+    if (!this.pool) {
+        return;
+    }
+
     this.featureCache[tier] = null;
     this.startFetchesForTiers([tier]);
 }
diff --git a/js/sourceadapters.js b/js/sourceadapters.js
index <HASH>..<HASH> 100644
--- a/js/sourceadapters.js
+++ b/js/sourceadapters.js
@@ -174,6 +174,10 @@ CachingFeatureSource.prototype.capabilities = function() {
 }
 
 CachingFeatureSource.prototype.fetch = function(chr, min, max, scale, types, pool, callback) {
+    if (pool == null) {
+        throw 'pool is null...';
+    }
+
     var awaitedFeatures = pool.awaitedFeatures[this.cfsid];
     if (!awaitedFeatures) {
         var awaitedFeatures = new Awaited();
Reject attempts to invalidate before first fetch.