diff --git a/src/dwarfs/similarity_ordering.cpp b/src/dwarfs/similarity_ordering.cpp
index 13789d61..6b10a4b8 100644
--- a/src/dwarfs/similarity_ordering.cpp
+++ b/src/dwarfs/similarity_ordering.cpp
@@ -26,6 +26,7 @@
 #include <unordered_map>
 #include <variant>
 
+#include <folly/Function.h>
 #include <folly/container/Enumerate.h>
 #include <folly/experimental/Bits.h>