diff --git a/src/num.cpp b/src/num.cpp
index 874a3828..195bf55e 100644
--- a/src/num.cpp
+++ b/src/num.cpp
@@ -16,6 +16,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <time.h>
 
 #include <string>