1 files changed, 5 insertions, 2 deletions
diff --git a/Source/cmFileMonitor.cxx b/Source/cmFileMonitor.cxx
index b55341b..9844306 100644
--- a/Source/cmFileMonitor.cxx
+++ b/Source/cmFileMonitor.cxx
@@ -247,7 +247,10 @@ public:
 
   void StopWatching() final {}
 
-  void AppendCallback(cmFileMonitor::Callback cb) { CbList.push_back(cb); }
+  void AppendCallback(cmFileMonitor::Callback const& cb)
+  {
+    this->CbList.push_back(cb);
+  }
 
   std::string Path() const final
   {
@@ -310,7 +313,7 @@ cmFileMonitor::~cmFileMonitor()
 }
 
 void cmFileMonitor::MonitorPaths(const std::vector<std::string>& paths,
-                                 Callback cb)
+                                 Callback const& cb)
 {
   for (const auto& p : paths) {
     std::vector<std::string> pathSegments;