diff --git a/src/tvhtime.c b/src/tvhtime.c
index 6b01883b..3cc33cb0 100644
--- a/src/tvhtime.c
+++ b/src/tvhtime.c
@@ -1,3 +1,5 @@
+#define _ISOC9X_SOURCE
+
 #include <time.h>
 #include <sys/ipc.h>
 #include <sys/shm.h>