diff --git a/sys/include/net/gnrc/tcp.h b/sys/include/net/gnrc/tcp.h
index fd66b8ced6..052f078b66 100644
--- a/sys/include/net/gnrc/tcp.h
+++ b/sys/include/net/gnrc/tcp.h
@@ -19,8 +19,8 @@
  * @author      Simon Brummer <simon.brummer@haw-hamburg.de>
  */
 
-#ifndef GNRC_TCP_H_
-#define GNRC_TCP_H_
+#ifndef GNRC_TCP_H
+#define GNRC_TCP_H
 
 #include "net/tcp.h"
 #include "net/gnrc/netapi.h"
@@ -210,5 +210,5 @@ gnrc_pktsnip_t *gnrc_tcp_hdr_build(gnrc_pktsnip_t *payload, uint16_t src, uint16
 }
 #endif
 
-#endif /* GNRC_TCP_H_ */
+#endif /* GNRC_TCP_H */
 /** @} */
diff --git a/sys/include/net/gnrc/tcp/config.h b/sys/include/net/gnrc/tcp/config.h
index b97c4ec0d5..1bc9ffe378 100644
--- a/sys/include/net/gnrc/tcp/config.h
+++ b/sys/include/net/gnrc/tcp/config.h
@@ -19,8 +19,8 @@
  * @author      Simon Brummer <simon.brummer@haw-hamburg.de>
  */
 
-#ifndef GNRC_TCP_CONFIG_H_
-#define GNRC_TCP_CONFIG_H_
+#ifndef GNRC_TCP_CONFIG_H
+#define GNRC_TCP_CONFIG_H
 
 #include "timex.h"
 
@@ -141,5 +141,5 @@ extern "C" {
 }
 #endif
 
-#endif /* GNRC_TCP_CONFIG_H_ */
+#endif /* GNRC_TCP_CONFIG_H */
 /** @} */
diff --git a/sys/include/net/gnrc/tcp/tcb.h b/sys/include/net/gnrc/tcp/tcb.h
index 205c63b91b..f34814e939 100644
--- a/sys/include/net/gnrc/tcp/tcb.h
+++ b/sys/include/net/gnrc/tcp/tcb.h
@@ -19,8 +19,8 @@
  * @author      Simon Brummer <simon.brummer@haw-hamburg.de>
  */
 
-#ifndef GNRC_TCP_TCB_H_
-#define GNRC_TCP_TCB_H_
+#ifndef GNRC_TCP_TCB_H
+#define GNRC_TCP_TCB_H
 
 #include <stdint.h>
 #include <ringbuffer.h>
@@ -86,5 +86,5 @@ typedef struct _transmission_control_block {
 #ifdef __cplusplus
 }
 #endif
-#endif /* GNRC_TCP_TCB_H_ */
+#endif /* GNRC_TCP_TCB_H */
 /** @} */
diff --git a/sys/net/gnrc/transport_layer/tcp/internal/common.h b/sys/net/gnrc/transport_layer/tcp/internal/common.h
index 4a3e4ddffd..bdaac64f61 100644
--- a/sys/net/gnrc/transport_layer/tcp/internal/common.h
+++ b/sys/net/gnrc/transport_layer/tcp/internal/common.h
@@ -19,8 +19,8 @@
  * @author     Simon Brummer <brummer.simon@googlemail.com>
  */
 
-#ifndef GNRC_TCP_INTERNAL_COMMON_H_
-#define GNRC_TCP_INTERNAL_COMMON_H_
+#ifndef GNRC_TCP_INTERNAL_COMMON_H
+#define GNRC_TCP_INTERNAL_COMMON_H
 
 #include <stdint.h>
 #include "kernel_types.h"
@@ -133,5 +133,5 @@ extern mutex_t _list_tcb_lock;
 }
 #endif
 
-#endif /* GNRC_TCP_INTERNAL_COMMON_H_ */
+#endif /* GNRC_TCP_INTERNAL_COMMON_H */
 /** @} */
diff --git a/sys/net/gnrc/transport_layer/tcp/internal/eventloop.h b/sys/net/gnrc/transport_layer/tcp/internal/eventloop.h
index 2dce76eff5..702b3ed730 100644
--- a/sys/net/gnrc/transport_layer/tcp/internal/eventloop.h
+++ b/sys/net/gnrc/transport_layer/tcp/internal/eventloop.h
@@ -19,8 +19,8 @@
  * @author     Simon Brummer <brummer.simon@googlemail.com>
  */
 
-#ifndef GNRC_TCP_INTERNAL_EVENTLOOP_H_
-#define GNRC_TCP_INTERNAL_EVENTLOOP_H_
+#ifndef GNRC_TCP_INTERNAL_EVENTLOOP_H
+#define GNRC_TCP_INTERNAL_EVENTLOOP_H
 
 #ifdef __cplusplus
 extern "C" {
@@ -39,5 +39,5 @@ void *_event_loop(__attribute__((unused)) void *arg);
 }
 #endif
 
-#endif /* GNRC_TCP_INTERNAL_EVENTLOOP_H_ */
+#endif /* GNRC_TCP_INTERNAL_EVENTLOOP_H */
 /** @} */
diff --git a/sys/net/gnrc/transport_layer/tcp/internal/fsm.h b/sys/net/gnrc/transport_layer/tcp/internal/fsm.h
index a9d724cae0..7efdc812da 100644
--- a/sys/net/gnrc/transport_layer/tcp/internal/fsm.h
+++ b/sys/net/gnrc/transport_layer/tcp/internal/fsm.h
@@ -19,8 +19,8 @@
  * @author     Simon Brummer <brummer.simon@googlemail.com>
  */
 
-#ifndef GNRC_TCP_INTERNAL_FSM_H_
-#define GNRC_TCP_INTERNAL_FSM_H_
+#ifndef GNRC_TCP_INTERNAL_FSM_H
+#define GNRC_TCP_INTERNAL_FSM_H
 
 #include <errno.h>
 #include "net/gnrc/pktbuf.h"
@@ -85,5 +85,5 @@ int _fsm(gnrc_tcp_tcb_t* tcb, fsm_event_t event, gnrc_pktsnip_t *in_pkt, void *b
 }
 #endif
 
-#endif /* GNRC_TCP_INTERNAL_FSM_H_ */
+#endif /* GNRC_TCP_INTERNAL_FSM_H */
 /** @} */
diff --git a/sys/net/gnrc/transport_layer/tcp/internal/option.h b/sys/net/gnrc/transport_layer/tcp/internal/option.h
index 0b58aa6830..775f50dead 100644
--- a/sys/net/gnrc/transport_layer/tcp/internal/option.h
+++ b/sys/net/gnrc/transport_layer/tcp/internal/option.h
@@ -19,8 +19,8 @@
  * @author     Simon Brummer <brummer.simon@googlemail.com>
  */
 
-#ifndef GNRC_TCP_INTERNAL_OPTION_H_
-#define GNRC_TCP_INTERNAL_OPTION_H_
+#ifndef GNRC_TCP_INTERNAL_OPTION_H
+#define GNRC_TCP_INTERNAL_OPTION_H
 
 #include "net/tcp.h"
 #include "net/gnrc/tcp.h"
@@ -63,5 +63,5 @@ int _option_parse(gnrc_tcp_tcb_t* tcb, tcp_hdr_t *hdr);
 }
 #endif
 
-#endif /* GNRC_TCP_INTERNAL_OPTION_H_*/
+#endif /* GNRC_TCP_INTERNAL_OPTION_H*/
 /** @} */
diff --git a/sys/net/gnrc/transport_layer/tcp/internal/pkt.h b/sys/net/gnrc/transport_layer/tcp/internal/pkt.h
index d63ff9c7ed..0a1ea93e2f 100644
--- a/sys/net/gnrc/transport_layer/tcp/internal/pkt.h
+++ b/sys/net/gnrc/transport_layer/tcp/internal/pkt.h
@@ -19,8 +19,8 @@
  * @author     Simon Brummer <brummer.simon@googlemail.com>
  */
 
-#ifndef GNRC_TCP_INTERNAL_PKT_H_
-#define GNRC_TCP_INTERNAL_PKT_H_
+#ifndef GNRC_TCP_INTERNAL_PKT_H
+#define GNRC_TCP_INTERNAL_PKT_H
 
 #include "net/conn/tcp.h"
 
@@ -146,5 +146,5 @@ uint16_t _pkt_calc_csum(const gnrc_pktsnip_t *hdr, const gnrc_pktsnip_t *pseudo_
 }
 #endif
 
-#endif /* GNRC_TCP_INTERNAL_PKT_H_ */
+#endif /* GNRC_TCP_INTERNAL_PKT_H */
 /** @} */
diff --git a/sys/net/gnrc/transport_layer/tcp/internal/rcvbuf.h b/sys/net/gnrc/transport_layer/tcp/internal/rcvbuf.h
index 39a68afe0a..2183061608 100644
--- a/sys/net/gnrc/transport_layer/tcp/internal/rcvbuf.h
+++ b/sys/net/gnrc/transport_layer/tcp/internal/rcvbuf.h
@@ -19,8 +19,8 @@
  * @author     Simon Brummer <brummer.simon@googlemail.com>
  * @}
  */
- #ifndef GNRC_TCP_INTERNAL_RCVBUF_H_
- #define GNRC_TCP_INTERNAL_RCVBUF_H_
+ #ifndef GNRC_TCP_INTERNAL_RCVBUF_H
+ #define GNRC_TCP_INTERNAL_RCVBUF_H
 
 #include <stdint.h>
 #include "mutex.h"
@@ -77,5 +77,5 @@ void _rcvbuf_release_buffer(gnrc_tcp_tcb_t* tcb);
 }
 #endif
 
-#endif /* GNRC_TCP_INTERNAL_RCVBUF_H_ */
+#endif /* GNRC_TCP_INTERNAL_RCVBUF_H */
 /** @} */