diff --git a/src/libtommath.cpp b/src/libtommath.cpp
index c1e1cfe34..6322089e6 100644
--- a/src/libtommath.cpp
+++ b/src/libtommath.cpp
@@ -1,3 +1,5 @@
+#define MP_USE_MEMOPS
+
 #include "libtommath/mp_2expt.c"
 #include "libtommath/mp_abs.c"
 #include "libtommath/mp_add.c"