diff --git a/tests/gamma.c b/tests/gamma.c
index c692cf9a..fbd37622 100644
--- a/tests/gamma.c
+++ b/tests/gamma.c
@@ -46,6 +46,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 static void error_callback(int error, const char* description)
 {