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--- a/src/utils/conftree.h
+++ b/src/utils/conftree.h
@@ -52,6 +52,7 @@
 #include <string>
 #include <map>
 #include <vector>
+#include <algorithm>
 
 // rh7.3 likes iostream better...
 #if defined(__GNUC__) && __GNUC__ < 3