diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index bd8f95e479..4b1aef9352 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1,3 +1,5 @@
+#include <algorithm>
+
 #include "build.hh"
 #include "eval.hh"
 #include "globals.hh"