diff --git a/Source/Modules/SessionCtl_Delegates.swift b/Source/Modules/SessionCtl_Delegates.swift
index 904d9443..c73c10cd 100644
--- a/Source/Modules/SessionCtl_Delegates.swift
+++ b/Source/Modules/SessionCtl_Delegates.swift
@@ -108,7 +108,9 @@ extension SessionCtl: CtlCandidateDelegate {
     return convertedCandidates
   }
 
-  public func candidatePairHighlightChanged(at _: Int) {}
+  public func candidatePairHighlightChanged(at theIndex: Int) {
+    inputHandler?.previewCompositionBufferForCandidate(at: theIndex)
+  }
 
   public func candidatePairSelectionConfirmed(at index: Int) {
     guard let inputHandler = inputHandler else { return }