diff --git a/src/frontends/lean/parser.cpp b/src/frontends/lean/parser.cpp
index d901f0f44..08051511e 100644
--- a/src/frontends/lean/parser.cpp
+++ b/src/frontends/lean/parser.cpp
@@ -8,6 +8,7 @@ Author: Leonardo de Moura
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <algorithm>
 #include <readline/readline.h>
 #include <readline/history.h>
 #endif