diff --git a/core/cib.c b/core/cib.c
index d8a7c0d68822de64c890192bc75b15ff0f0f989f..39150dd4697730a46a509dc5a785db8ce2f7c890 100644
--- a/core/cib.c
+++ b/core/cib.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/core/lifo.c b/core/lifo.c
index 846d3741ee4f01908a0c0807ac6e7a76b7dbe048..a6032558aa0542e6c1f6ca68974e3dea0df9640f 100644
--- a/core/lifo.c
+++ b/core/lifo.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/cpu/lpc1768/atom.c b/cpu/lpc1768/atom.c
index 94e98fe4745ec6c302b6d8e88dc0ed5a4e5bf754..e8ecc4fc1a75b972653168ef312f62539213de7f 100644
--- a/cpu/lpc1768/atom.c
+++ b/cpu/lpc1768/atom.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2013 Oliver Hahm <oliver.hahm@inria.fr>
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  *
diff --git a/cpu/lpc1768/cpu.c b/cpu/lpc1768/cpu.c
index b056283528514c5e66d0c0ed99f3d8dc7795b75a..505ff96d30fd9de181ab94291afad851d2514ec8 100644
--- a/cpu/lpc1768/cpu.c
+++ b/cpu/lpc1768/cpu.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2013 Oliver Hahm <oliver.hahm@inria.fr>
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  *
diff --git a/cpu/lpc1768/lpc1768-lpm.c b/cpu/lpc1768/lpc1768-lpm.c
index 832e6ecd46a70650dc83df6683405d2e03290f73..c4541a8e0ebeb2dab689dcbc4b30481c773e2a64 100644
--- a/cpu/lpc1768/lpc1768-lpm.c
+++ b/cpu/lpc1768/lpc1768-lpm.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2013 Oliver Hahm <oliver.hahm@inria.fr>
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  *
diff --git a/cpu/lpc1768/syscalls.c b/cpu/lpc1768/syscalls.c
index 4b6031fb7b40be1d17108b5ef9b996cb2ac2fa8d..1160a7c830a27564d2b27dfa2901433261721ea2 100644
--- a/cpu/lpc1768/syscalls.c
+++ b/cpu/lpc1768/syscalls.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2013 Oliver Hahm <oliver.hahm@inria.fr>
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  *
diff --git a/cpu/sam3x8e/cpu.c b/cpu/sam3x8e/cpu.c
index 998ae82aba794c56e620e552180a7b56807f8ccc..5498c68b9d34ebfe63b665c5c673257ffb77859f 100644
--- a/cpu/sam3x8e/cpu.c
+++ b/cpu/sam3x8e/cpu.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2014 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/examples/default/main.c b/examples/default/main.c
index 02f8464bbcdb9033183a48fb9bb3136abcc1a92b..5ee0b056ec56fcad4b044ee9ffe512f5954696e0 100644
--- a/examples/default/main.c
+++ b/examples/default/main.c
@@ -3,7 +3,7 @@
  * Copyright (C) 2013 INRIA
  * Copyright (C) 2013 Ludwig Ortmann <ludwig.ortmann@fu-berlin.de>
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/fd.c b/sys/posix/fd.c
index 9d05475428e96ff89a40f9696e2a373e8fcc19cc..54e9ea505a90784377dfd43eed9e3375f416f6aa 100644
--- a/sys/posix/fd.c
+++ b/sys/posix/fd.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pnet/netinet_in.c b/sys/posix/pnet/netinet_in.c
index 908e19a3eaa14ce138cb802cdbeb573a6ad9a2be..72208e969bb60f619ddfab320ad52fd4dc645bf2 100644
--- a/sys/posix/pnet/netinet_in.c
+++ b/sys/posix/pnet/netinet_in.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pnet/sys_socket.c b/sys/posix/pnet/sys_socket.c
index 13a335b72ed5ed93a9325a78de891db7acdd03ac..a68c1e7db5e6c35dc54dfb768fb86876b633af42 100644
--- a/sys/posix/pnet/sys_socket.c
+++ b/sys/posix/pnet/sys_socket.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pthread/pthread.c b/sys/posix/pthread/pthread.c
index 99193b3bfa7d367ea3f14b67b88c8bca1afb939e..1a0f30d72c5d1ed957cb5b036a11cbcb2e16096b 100644
--- a/sys/posix/pthread/pthread.c
+++ b/sys/posix/pthread/pthread.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pthread/pthread_attr.c b/sys/posix/pthread/pthread_attr.c
index de37963836e33b9a0998115937dabe8f05f12d20..7f4ef94f7b2fc2609311edf27d17601318614302 100644
--- a/sys/posix/pthread/pthread_attr.c
+++ b/sys/posix/pthread/pthread_attr.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pthread/pthread_barrier.c b/sys/posix/pthread/pthread_barrier.c
index fc4a24913f024f14dc4a74d3f966034a5acbd218..22165441b57c6e674bab3fce6ea11d595960c34b 100644
--- a/sys/posix/pthread/pthread_barrier.c
+++ b/sys/posix/pthread/pthread_barrier.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2014 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pthread/pthread_barrierattr.c b/sys/posix/pthread/pthread_barrierattr.c
index c0b5d96f65305d315061b94a77607acc2ac57bc5..543a0313b4e56f7e8eacf1362adfb92dc4e8426c 100644
--- a/sys/posix/pthread/pthread_barrierattr.c
+++ b/sys/posix/pthread/pthread_barrierattr.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2014 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pthread/pthread_mutex.c b/sys/posix/pthread/pthread_mutex.c
index 295d940b6f89f0f033b064af8927ac049ffe14e7..1b78844f5339559489d92185ac59b9dc2ded7f64 100644
--- a/sys/posix/pthread/pthread_mutex.c
+++ b/sys/posix/pthread/pthread_mutex.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pthread/pthread_once.c b/sys/posix/pthread/pthread_once.c
index 9f9d10a70c54866dd3a51330ec88f2a3928240cb..200378bcaa40dd4f77bd637f0e8da8a675e067f2 100644
--- a/sys/posix/pthread/pthread_once.c
+++ b/sys/posix/pthread/pthread_once.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/pthread/pthread_spin.c b/sys/posix/pthread/pthread_spin.c
index 5bc2ee839ad807b253e115025c1a3fb0e4eb6063..501bb93f92463071ff6e4dd48d4d1e85d9b3887c 100644
--- a/sys/posix/pthread/pthread_spin.c
+++ b/sys/posix/pthread/pthread_spin.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/strings.c b/sys/posix/strings.c
index abd011b653b5f0f56838d8d4fda5eb27096b034e..ef9c1bba172a30fa1752f21f1fdd787450cbe39d 100644
--- a/sys/posix/strings.c
+++ b/sys/posix/strings.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/sys/posix/unistd.c b/sys/posix/unistd.c
index dfc484dd78f416555f4ee27fb40fc4e081519c5e..92222e4b085217acdf268d57772a4b8b224abd29 100644
--- a/sys/posix/unistd.c
+++ b/sys/posix/unistd.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */
diff --git a/tests/test_net_if/main.c b/tests/test_net_if/main.c
index 956af778821be191c0d55a578b0d8852b711ff30..c9af411703a05d1d091a81a82e9ca2cb94120728 100644
--- a/tests/test_net_if/main.c
+++ b/tests/test_net_if/main.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2013 Martin Lenders <mlenders@inf.fu-berlin.de>
  *
- * This file subject to the terms and conditions of the GNU Lesser General
+ * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License. See the file LICENSE in the top level directory for more
  * details.
  */