diff --git a/src/map.rs b/src/map.rs
index 6032c339..76993c36 100644
--- a/src/map.rs
+++ b/src/map.rs
@@ -725,7 +725,7 @@ where
     /// The comparison function receives two key and value pairs to compare (you
     /// can sort by keys or values or their combination as needed).
     ///
-    /// Computes in **O(n log n + c)** time and **O(n)** space where *n* is
+    /// Computes in **O(n log n + c)** time where *n* is
     /// the length of the map and *c* is the capacity. The sort is unstable.
     pub fn sort_unstable_by<F>(&mut self, mut cmp: F)
     where
diff --git a/src/set.rs b/src/set.rs
index 72a386c5..ddd1cc38 100644
--- a/src/set.rs
+++ b/src/set.rs
@@ -596,7 +596,7 @@ where
 
     /// Sort the set's values in place using the comparison funtion `cmp`.
     ///
-    /// Computes in **O(n log n)** time and **O(n)** space. The sort is unstable.
+    /// Computes in **O(n log n)** time. The sort is unstable.
     pub fn sort_unstable_by<F>(&mut self, mut cmp: F)
     where
         F: FnMut(&T, &T) -> Ordering,