diff --git a/README.rst b/README.rst
index cda6a66..c3d4ad3 100644
--- a/README.rst
+++ b/README.rst
@@ -82,6 +82,17 @@ Required
 .. |yosys| replace:: ``yosys``
 .. _yosys: https://github.com/YosysHQ/yosys
 
+By default, `verilog-diagram` uses the `yowasp-yosys` package provided in PyPI. It can be installed by running `pip install -r requirements.txt`.
+However, you could also use the `yosys` that is installed on your system, by adding the following line in `setup(app)` inside conf.py.
+
+.. code-block:: py
+
+   def setup(app):
+      ...
+      VerilogDiagram.use_yowasp = False
+      ...
+
+
 Optional
 ~~~~~~~~
 
diff --git a/docs/conf.py b/docs/conf.py
index f4f2e2f..e728d9a 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -37,6 +37,7 @@
 #
 import os
 import sys
+from sphinxcontrib_verilog_diagrams import VerilogDiagram
 sys.path.insert(0, os.path.abspath('..'))
 
 # -- General configuration ------------------------------------------------
@@ -251,3 +252,7 @@
 
 # Example configuration for intersphinx: refer to the Python standard library.
 intersphinx_mapping = {'https://docs.python.org/': None}
+
+def setup(app):
+    # VerilogDiagram.use_yowasp = False
+    pass
diff --git a/environment.yml b/environment.yml
index 30e7597..f7c4f2b 100644
--- a/environment.yml
+++ b/environment.yml
@@ -11,7 +11,6 @@ dependencies:
 - pip
 - python=3.7
 - sphinx
-- yosys
 - pip:          # Packages installed from PyPI
   - -r file:requirements.txt
   - -r file:docs/requirements.txt
diff --git a/requirements.txt b/requirements.txt
index 15df521..2626b19 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,5 +2,7 @@ setuptools
 docutils
 sphinx
 
+yowasp-yosys>=0.9.post4547.dev9
+
 # Needed to upload to PyPi
 twine
diff --git a/sphinxcontrib_verilog_diagrams/__init__.py b/sphinxcontrib_verilog_diagrams/__init__.py
index 7330284..21ccae1 100644
--- a/sphinxcontrib_verilog_diagrams/__init__.py
+++ b/sphinxcontrib_verilog_diagrams/__init__.py
@@ -148,6 +148,8 @@ class VerilogDiagram(Directive):
 
     final_argument_whitespace = False
 
+    use_yowasp = True
+
     option_spec = {
         'type': str,
         'module': str,
@@ -208,9 +210,14 @@ def run(self):
 
 
 def run_yosys(src, cmd):
-    ycmd = "yosys -p '{cmd}' {src}".format(src=src, cmd=cmd)
-    print("Running yosys:", ycmd)
-    subprocess.check_output(ycmd, shell=True)
+    print("Running yosys: yosys -q -p", "'{}'".format(cmd), src)
+    if VerilogDiagram.use_yowasp:
+        import yowasp_yosys
+        ycmd = ["-q", "-p", "{}".format(cmd), src]
+        yowasp_yosys.run_yosys(ycmd)
+    else:
+        ycmd = "yosys -p '{cmd}' {src}".format(src=src, cmd=cmd)
+        subprocess.check_output(ycmd, shell=True)
 
 
 def diagram_yosys(ipath, opath, module='top', flatten=False):
@@ -232,6 +239,12 @@ def diagram_yosys(ipath, opath, module='top', flatten=False):
 """.format(top=module, flatten=flatten, fmt=oext, oprefix=oprefix).strip(),
     )
 
+    if VerilogDiagram.use_yowasp:
+        # somehow yowasp_yosys fails to execute `dot` to convert the dot file to svg,
+        # which works on native yosys, perhaps a limitation with wasm
+        svgdata = subprocess.check_output(["dot", "-Tsvg", "{}.dot".format(oprefix)])
+        open("{}.svg".format(oprefix), "wb").write(svgdata)
+
     assert path.exists(opath), 'Output file {} was not created!'.format(oopath)
     print('Output file created: {}'.format(opath))
 
@@ -268,7 +281,7 @@ def diagram_netlistsvg(ipath, opath, module='top', flatten=False):
     run_yosys(
         src=ipath,
         cmd = """\
-prep -top {top} {flatten}; cd {top}; write_json {ojson}
+prep -top {top} {flatten}; cd {top}; write_json -compat-int {ojson}
 """.format(top=module, flatten=flatten, ojson=ojson).strip())
     assert path.exists(ojson), 'Output file {} was not created!'.format(ojson)