diff --git a/modules/osp/timeapi.c b/modules/osp/timeapi.c
index 7321030ce03..8739c56acdc 100644
--- a/modules/osp/timeapi.c
+++ b/modules/osp/timeapi.c
@@ -32,21 +32,10 @@
  *  2016-01-25  Time related functions.
  */
 
-#define _XOPEN_SOURCE 600          /* glibc2 on linux, bsd */
-#define _XOPEN_SOURCE_EXTENDED 1   /* solaris */
-
-/**
- *  * _XOPEN_SOURCE creates conflict in swab definition in Solaris
- *   */
-#ifdef __OS_solaris
-    #undef _XOPEN_SOURCE
-#endif
-
+/* make strptime available */
+#define _GNU_SOURCE
 #include <time.h>
 
-#undef _XOPEN_SOURCE
-#undef _XOPEN_SOURCE_EXTENDED
-
 #include <stdlib.h>
 #include <osp/osp.h>
 #include "../../dprint.h"
diff --git a/modules/stir_shaken/stir_shaken.c b/modules/stir_shaken/stir_shaken.c
index 3583bb6589f..60276d3f865 100644
--- a/modules/stir_shaken/stir_shaken.c
+++ b/modules/stir_shaken/stir_shaken.c
@@ -33,22 +33,10 @@
  *
  */
 
+/* make strptime available */
 #define _GNU_SOURCE
-#define _XOPEN_SOURCE 600          /* glibc2 on linux, bsd */
-#define _XOPEN_SOURCE_EXTENDED 1   /* solaris */
-
-/**
- * _XOPEN_SOURCE creates conflict in swab definition in Solaris
- */
-#ifdef __OS_solaris
-	#undef _XOPEN_SOURCE
-#endif
-
 #include <time.h>
 
-#undef _XOPEN_SOURCE
-#undef _XOPEN_SOURCE_EXTENDED
-
 #include <openssl/x509.h>
 
 #undef _GNU_SOURCE
diff --git a/transformations.c b/transformations.c
index 443a8376cc7..68e108de15c 100644
--- a/transformations.c
+++ b/transformations.c
@@ -23,22 +23,10 @@
  * \brief Support for transformations
  */
 
+/* make strptime available */
 #define _GNU_SOURCE
-#define _XOPEN_SOURCE 600          /* glibc2 on linux, bsd */
-#define _XOPEN_SOURCE_EXTENDED 1   /* solaris */
-
-/**
- * _XOPEN_SOURCE creates conflict in swab definition in Solaris
- */
-#ifdef __OS_solaris
-	#undef _XOPEN_SOURCE
-#endif
-
 #include <time.h>
 
-#undef _XOPEN_SOURCE
-#undef _XOPEN_SOURCE_EXTENDED
-
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>