diff --git a/zed/src/editor/buffer.rs b/zed/src/editor/buffer.rs
index 82e6818bfc79da69a9595b092cfbd2b9a68a926d..fe43bf2e67baa7cb6809d8d1d38ca0316d297997 100644
--- a/zed/src/editor/buffer.rs
+++ b/zed/src/editor/buffer.rs
@@ -2128,17 +2128,6 @@ impl<'a> sum_tree::SeekDimension<'a, FragmentSummary> for VersionedOffset {
     }
 }
 
-impl<'a, T, U> sum_tree::Dimension<'a, FragmentSummary> for (T, U)
-where
-    T: sum_tree::Dimension<'a, FragmentSummary>,
-    U: sum_tree::Dimension<'a, FragmentSummary>,
-{
-    fn add_summary(&mut self, summary: &'a FragmentSummary, cx: &Option<time::Global>) {
-        self.0.add_summary(summary, cx);
-        self.1.add_summary(summary, cx);
-    }
-}
-
 impl Operation {
     fn replica_id(&self) -> ReplicaId {
         self.lamport_timestamp().replica_id
diff --git a/zed/src/sum_tree.rs b/zed/src/sum_tree.rs
index 35b91833761027d2edd71f089c7ad1e5057ad28f..48338d4a57f281ef763677354999c899a776d724 100644
--- a/zed/src/sum_tree.rs
+++ b/zed/src/sum_tree.rs
@@ -36,6 +36,18 @@ impl<'a, T: Summary> Dimension<'a, T> for () {
     fn add_summary(&mut self, _: &'a T, _: &T::Context) {}
 }
 
+impl<'a, S, D1, D2> Dimension<'a, S> for (D1, D2)
+where
+    S: Summary,
+    D1: Dimension<'a, S>,
+    D2: Dimension<'a, S>,
+{
+    fn add_summary(&mut self, summary: &'a S, cx: &S::Context) {
+        self.0.add_summary(summary, cx);
+        self.1.add_summary(summary, cx);
+    }
+}
+
 pub trait SeekDimension<'a, T: Summary>: Dimension<'a, T> {
     fn cmp(&self, other: &Self, cx: &T::Context) -> Ordering;
 }