diff --git a/plugins/prospector.cpp b/plugins/prospector.cpp
index 2f9f5b5d3..8b505c221 100644
--- a/plugins/prospector.cpp
+++ b/plugins/prospector.cpp
@@ -10,6 +10,7 @@
 #include <iomanip>
 #include <map>
 #include <algorithm>
+#include <functional>
 #include <vector>
 
 using namespace std;