diff --git a/container/Cargo.toml b/container/Cargo.toml
index 88d2ef563..baed97e41 100644
--- a/container/Cargo.toml
+++ b/container/Cargo.toml
@@ -7,5 +7,6 @@ license = "MIT"
 
 [dependencies]
 columnation = { git = "https://github.com/frankmcsherry/columnation" }
-flatcontainer = "0.5"
+# flatcontainer = "0.5"
+flatcontainer = { git = "https://github.com/antiguru/flatcontainer" }
 serde = { version = "1.0"}
diff --git a/container/src/flatcontainer.rs b/container/src/flatcontainer.rs
index 62600a77e..441445e97 100644
--- a/container/src/flatcontainer.rs
+++ b/container/src/flatcontainer.rs
@@ -1,9 +1,14 @@
 //! Present a [`FlatStack`] as a timely container.
 
 pub use flatcontainer::*;
+use flatcontainer::impls::offsets::OffsetContainer;
 use crate::{buffer, Container, SizableContainer, PushInto};
 
-impl<R: Region + Clone + 'static> Container for FlatStack<R> {
+impl<R, S> Container for FlatStack<R, S>
+where
+    R: Region + Clone + 'static,
+    S: OffsetContainer<<R as Region>::Index> + Clone + 'static,
+{
     type ItemRef<'a> = R::ReadItem<'a>  where Self: 'a;
     type Item<'a> = R::ReadItem<'a> where Self: 'a;
 
@@ -28,6 +33,7 @@ impl<R: Region + Clone + 'static> Container for FlatStack<R> {
     }
 }
 
+// Only implemented for `FlatStack` with `Vec` offsets.
 impl<R: Region + Clone + 'static> SizableContainer for FlatStack<R> {
     fn capacity(&self) -> usize {
         self.capacity()
@@ -42,7 +48,12 @@ impl<R: Region + Clone + 'static> SizableContainer for FlatStack<R> {
     }
 }
 
-impl<R: Region + Push<T>, T> PushInto<T> for FlatStack<R> {
+impl<R, S, T> PushInto<T> for FlatStack<R, S>
+where
+    R: Region + Push<T>,
+    S: OffsetContainer<R::Index> + Clone + 'static,
+    for<'a> &'a S: IntoIterator<Item = &'a R::Index>,
+{
     #[inline]
     fn push_into(&mut self, item: T) {
         self.copy(item);