--- a/libmamba/include/mamba/util/random.hpp
+++ b/libmamba/include/mamba/util/random.hpp
@@ -11,6 +11,7 @@
 #include <algorithm>
 #include <array>
 #include <cstring>
+#include <functional>
 #include <limits>
 #include <random>
 #include <string>