diff --git a/lib/src/async_cache.dart b/lib/src/async_cache.dart
index c2d7c01..36dec01 100644
--- a/lib/src/async_cache.dart
+++ b/lib/src/async_cache.dart
@@ -37,13 +37,6 @@
   /// Fires when the cache should be considered stale.
   Timer _stale;
 
-  /// Creates a cache that invalidates after an in-flight request is complete.
-  ///
-  /// An ephemeral cache guarantees that a callback function will only be
-  /// executed at most once concurrently. This is useful for requests for which
-  /// data is updated frequently but stale data is acceptable.
-  factory AsyncCache.ephemeral() => new AsyncCache(Duration.zero);
-
   /// Creates a cache that invalidates its contents after [duration] has passed.
   ///
   /// The [duration] starts counting after the Future returned by [fetch]
@@ -51,6 +44,13 @@
   /// event.
   AsyncCache(this._duration);
 
+  /// Creates a cache that invalidates after an in-flight request is complete.
+  ///
+  /// An ephemeral cache guarantees that a callback function will only be
+  /// executed at most once concurrently. This is useful for requests for which
+  /// data is updated frequently but stale data is acceptable.
+  factory AsyncCache.ephemeral() => new AsyncCache(Duration.zero);
+
   /// Returns a cached value from a previous call to [fetch], or runs [callback]
   /// to compute a new one.
   ///
@@ -89,13 +89,16 @@
   }
 
   /// Removes any cached value.
-  Future invalidate() {
+  Null invalidate() {
     _cachedValueFuture = null;
-    Future invalidate = _cachedStreamSplitter?.close();
+    // TODO: This does not await, but probably should.
+    _cachedStreamSplitter?.close();
     _cachedStreamSplitter = null;
     _stale?.cancel();
     _stale = null;
-    return invalidate;
+
+    // TODO: This does not return a future, but probably should.
+    return null;
   }
 
   void _startStaleTimer() {