diff --git a/lib/font.c b/lib/font.c
index a0a9ae6..57515da 100644
--- a/lib/font.c
+++ b/lib/font.c
@@ -1,21 +1,8 @@
-/* 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/>.
- *
- */
 /** monospace pixel fonts collection (code)
  *  @file
  *  @author King Kévin <kingkevin@cuvoodoo.info>
  *  @date 2018
+ *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
  */
 #include <stdint.h> // standard integer types
 #include "font.h" // own definitions
diff --git a/lib/font.h b/lib/font.h
index b70a802..ddb0a8f 100644
--- a/lib/font.h
+++ b/lib/font.h
@@ -1,20 +1,7 @@
-/* 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/>.
- *
- */
 /** monospace pixel fonts collection (API)
  *  @file
  *  @author King Kévin <kingkevin@cuvoodoo.info>
+ *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
  *  @date 2018
  */
 #pragma once
diff --git a/lib/oled_text.c b/lib/oled_text.c
index cc2789b..5df94d3 100644
--- a/lib/oled_text.c
+++ b/lib/oled_text.c
@@ -1,21 +1,8 @@
-/* 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/>.
- *
- */
 /** library to show display text on SSD1306 OLED display
  *  @file
  *  @author King Kévin <kingkevin@cuvoodoo.info>
  *  @date 2020
+ *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
  *  @note peripherals used: I²C @ref oled_ssd1306_i2c
  */
 /* standard libraries */
diff --git a/lib/oled_text.h b/lib/oled_text.h
index f584c23..26d7e48 100644
--- a/lib/oled_text.h
+++ b/lib/oled_text.h
@@ -1,21 +1,8 @@
-/* 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/>.
- *
- */
 /** library to show display text on SSD1306 OLED display
  *  @file
  *  @author King Kévin <kingkevin@cuvoodoo.info>
  *  @date 2018-2020
+ *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
  *  @note peripherals used: I²C @ref oled_ssd1306_i2c
  */
 #include "font.h"