diff --git a/test/test42.c b/test/test42.c
index ec1f1a806..12b726cbf 100644
--- a/test/test42.c
+++ b/test/test42.c
@@ -1,5 +1,4 @@
 /* Tests for MINIX3 ptrace(2) - by D.C. van Moolenbroek */
-#define _POSIX_SOURCE 1
 #include <setjmp.h>
 #include <stdlib.h>
 #include <stdio.h>
diff --git a/test/test43.c b/test/test43.c
index 354af2a14..e06838af9 100644
--- a/test/test43.c
+++ b/test/test43.c
@@ -1,5 +1,4 @@
 /* Tests for MINIX3 realpath(3) - by Erik van der Kouwe */
-#define _POSIX_SOURCE 1
 #include <assert.h>
 #include <dirent.h>
 #include <errno.h>
diff --git a/test/test50.c b/test/test50.c
index 3733f7f62..6c2d6a69d 100644
--- a/test/test50.c
+++ b/test/test50.c
@@ -1,5 +1,4 @@
 /* Tests for truncate(2) call family - by D.C. van Moolenbroek */
-#define _POSIX_SOURCE 1
 #include <sys/stat.h>
 #include <sys/param.h>
 #include <unistd.h>
diff --git a/test/test52.c b/test/test52.c
index c4fd6a7f9..1ac0e2f6a 100644
--- a/test/test52.c
+++ b/test/test52.c
@@ -1,4 +1,3 @@
-#define _POSIX_SOURCE 1
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>