diff --git a/test/test_connections.c b/test/test_connections.c
index 3dd4d082..61366b06 100644
--- a/test/test_connections.c
+++ b/test/test_connections.c
@@ -5,6 +5,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <string.h>
 #include <vips/vips.h>
 
 typedef struct _MyInput {