diff --git a/src/CalcManager/Ratpack/num.cpp b/src/CalcManager/Ratpack/num.cpp
index f25687b0..7b45fea0 100644
--- a/src/CalcManager/Ratpack/num.cpp
+++ b/src/CalcManager/Ratpack/num.cpp
@@ -18,6 +18,7 @@
 //
 //-----------------------------------------------------------------------------
 #include <list>
+#include <cstring> // for memmove
 #include "ratpak.h"
 
 using namespace std;