diff --git a/src/libespeak-ng/debug.c b/src/libespeak-ng/debug.c
index c5fd29ba..3c56407b 100644
--- a/src/libespeak-ng/debug.c
+++ b/src/libespeak-ng/debug.c
@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2007 by Jonathan Duddington
+ * email: jonsd@users.sourceforge.net
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #include <stdio.h>
 #include <stdarg.h>
 #include "speech.h"
diff --git a/src/libespeak-ng/debug.h b/src/libespeak-ng/debug.h
index 5f52c902..45fd203d 100644
--- a/src/libespeak-ng/debug.h
+++ b/src/libespeak-ng/debug.h
@@ -1,3 +1,22 @@
+/*
+ * Copyright (C) 2007 to 2009 by Jonathan Duddington
+ * email: jonsd@users.sourceforge.net
+ * Copyright (C) 2015 Reece H. Dunn
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #ifndef DEBUG_H
 #define DEBUG_H
 
diff --git a/src/libespeak-ng/espeak_command.h b/src/libespeak-ng/espeak_command.h
index b91cd2b2..0dde422e 100644
--- a/src/libespeak-ng/espeak_command.h
+++ b/src/libespeak-ng/espeak_command.h
@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2007, Gilles Casse <gcasse@oralux.org>
+ * Copyright (C) 2015 Reece H. Dunn
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #ifndef ESPEAK_COMMAND_H
 #define ESPEAK_COMMAND_H
 
diff --git a/src/libespeak-ng/event.h b/src/libespeak-ng/event.h
index 8abe83f7..c871024e 100644
--- a/src/libespeak-ng/event.h
+++ b/src/libespeak-ng/event.h
@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2007, Gilles Casse <gcasse@oralux.org>
+ * Copyright (C) 2015 Reece H. Dunn
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #ifndef EVENT_H
 #define EVENT_H
 
diff --git a/src/libespeak-ng/fifo.h b/src/libespeak-ng/fifo.h
index b846cf36..da06a5f4 100644
--- a/src/libespeak-ng/fifo.h
+++ b/src/libespeak-ng/fifo.h
@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2007, Gilles Casse <gcasse@oralux.org>
+ * Copyright (C) 2015 Reece H. Dunn
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #ifndef FIFO_H
 #define FIFO_H
 
diff --git a/src/libespeak-ng/klatt.h b/src/libespeak-ng/klatt.h
index 3e9ee082..f4f43145 100644
--- a/src/libespeak-ng/klatt.h
+++ b/src/libespeak-ng/klatt.h
@@ -1,3 +1,26 @@
+/*
+ * Copyright (C) 2008 by Jonathan Duddington
+ * email: jonsd@users.sourceforge.net
+ * Copyright (C) 2015 Reece H. Dunn
+ *
+ * Based on a re-implementation by:
+ * (c) 1993,94 Jon Iles and Nick Ing-Simmons
+ * of the Klatt cascade-parallel formant synthesizer
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #ifdef __cplusplus
 extern "C"
 {
diff --git a/src/libespeak-ng/sintab.h b/src/libespeak-ng/sintab.h
index 984bbbd3..4a84d12d 100644
--- a/src/libespeak-ng/sintab.h
+++ b/src/libespeak-ng/sintab.h
@@ -1,3 +1,22 @@
+/*
+ * Copyright (C) 2007 by Jonathan Duddington
+ * email: jonsd@users.sourceforge.net
+ * Copyright (C) 2015 Reece H. Dunn
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #ifdef __cplusplus
 extern "C"
 {
diff --git a/src/libespeak-ng/wave.h b/src/libespeak-ng/wave.h
index 2ce20593..50a893a8 100644
--- a/src/libespeak-ng/wave.h
+++ b/src/libespeak-ng/wave.h
@@ -1,3 +1,22 @@
+/*
+ * Copyright (C) 2007, Gilles Casse <gcasse@oralux.org>
+ * Copyright (C) 2015 Reece H. Dunn
+ * based on AudioIO.cc (Audacity-1.2.4b) and wavegen.cpp
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see: <http://www.gnu.org/licenses/>.
+ */
+
 #ifndef WAVE_H
 #define WAVE_H