diff --git a/src/support.c b/src/support.c
index d34f8b3..8fef62e 100644
--- a/src/support.c
+++ b/src/support.c
@@ -6,6 +6,7 @@
  */
 
 #include <string.h>
+#include <stdlib.h>
 
 #if LIBFTDI1 == 1
 #include <libftdi1/ftdi.h>