diff --git a/include/internal/clara.h b/include/internal/clara.h
index b2ffc586..c7c5052f 100644
--- a/include/internal/clara.h
+++ b/include/internal/clara.h
@@ -25,6 +25,7 @@
 #include <string>
 #include <vector>
 #include <map>
+#include <algorithm>
 
 // Use optional outer namespace
 #ifdef CLICHE_CLARA_OUTER_NAMESPACE