1 files changed, 4 insertions, 4 deletions
diff --git a/doc/using/Synthesis.rst b/doc/using/Synthesis.rst
index d3968fe67..953e0ec8b 100644
--- a/doc/using/Synthesis.rst
+++ b/doc/using/Synthesis.rst
@@ -138,7 +138,7 @@ Assertions, PSL and formal verification
 
   Treat all PSL asserts like PSL assumes. If this option is used, GHDL generates an `assume` directive
   for each `assert` directive during synthesis. This is similar to the `-assert-assumes`
-  option of Yosys' `read_verilog <http://www.clifford.at/yosys/cmd_read_verilog.html>`_ command.
+  option of Yosys' `read_verilog <https://yosyshq.net/yosys/cmd_read_verilog.html>`_ command.
 
   Example::
 
@@ -152,7 +152,7 @@ Assertions, PSL and formal verification
 
   Treat all PSL assumes like PSL asserts. If this option is used, GHDL generates an `assert` directive
   for each `assume` directive during synthesis. This is similar to the `-assume-asserts`
-  option of Yosys' `read_verilog <http://www.clifford.at/yosys/cmd_read_verilog.html>`_ command.
+  option of Yosys' `read_verilog <https://yosyshq.net/yosys/cmd_read_verilog.html>`_ command.
 
   Example::
 
@@ -167,7 +167,7 @@ Yosys plugin
 ************
 
 `ghdl-yosys-plugin <https://github.com/ghdl/ghdl-yosys-plugin>`_ is a module to use GHDL as a VHDL front-end for `Yosys
-Open Synthesis Suite <http://www.clifford.at/yosys/>`_, a framework for optimised synthesis and technology mapping.
+Open Synthesis Suite <https://yosyshq.net/yosys/>`_, a framework for optimised synthesis and technology mapping.
 Artifacts generated by Yosys can be used in multiple open source and vendor tools to achieve P&R, formal verification,
 etc. A relevant feature of combining GHDL and Yosys is that mixed-language (VHDL-Verilog) synthesis with open source
 tools is possible.
@@ -190,7 +190,7 @@ Yosys provides ``write_*`` commands for generating output netlists in different
 sources can be converted to EDIF, SMT, BTOR2, etc.
 
 .. HINT:: For a comprehensive list of supported output formats (AIGER, BLIF, ILANG, JSON...), check out the
-  `Yosys documentation <http://www.clifford.at/yosys/documentation.html>`_.
+  `Yosys documentation <https://yosyshq.net/yosys/documentation.html>`_.
 
 To Verilog
 ----------