diff --git a/cpp/include/raft/spatial/knn/detail/ball_cover.cuh b/cpp/include/raft/spatial/knn/detail/ball_cover.cuh
index 2b245d06cb..4911582ed9 100644
--- a/cpp/include/raft/spatial/knn/detail/ball_cover.cuh
+++ b/cpp/include/raft/spatial/knn/detail/ball_cover.cuh
@@ -45,6 +45,7 @@
 #include <thrust/functional.h>
 #include <thrust/reduce.h>
 #include <thrust/sequence.h>
+#include <thrust/sort.h>
 
 namespace raft {
 namespace spatial {