diff --git a/Licenses/README b/Licenses/README
index 9b9a462..731d45c 100644
--- a/Licenses/README
+++ b/Licenses/README
@@ -67,3 +67,4 @@ BSD 3-clause "New" or "Revised" License		BSD-3-Clause	Y		bsd-3-clause.txt	http:/
 IBM PIBS (PowerPC Initialization and		IBM-pibs			ibm-pibs.txt
 	Boot Software) license
 ISC License					ISC		Y		isc.txt			https://spdx.org/licenses/ISC
+X11 License					X11				x11.txt			https://spdx.org/licenses/X11.html
diff --git a/Licenses/x11.txt b/Licenses/x11.txt
new file mode 100644
index 0000000..23a3c63
--- /dev/null
+++ b/Licenses/x11.txt
@@ -0,0 +1,25 @@
+X11 License
+Copyright (C) 1996 X Consortium
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE X
+CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of the X Consortium shall not be
+used in advertising or otherwise to promote the sale, use or other dealings in
+this Software without prior written authorization from the X Consortium.
+
+X Window System is a trademark of X Consortium, Inc.