diff --git a/src/EbmlUnicodeString.cpp b/src/EbmlUnicodeString.cpp
index 80535b4d..2ba015f4 100644
--- a/src/EbmlUnicodeString.cpp
+++ b/src/EbmlUnicodeString.cpp
@@ -12,6 +12,7 @@
 
 #include "lib/utf8-cpp/source/utf8/checked.h"
 
+#include <algorithm>
 #include <cstring>
 
 namespace libebml {