diff --git a/sphinxcontrib_verilog_diagrams.py b/sphinxcontrib_verilog_diagrams.py
index 972db9f..a0001f9 100644
--- a/sphinxcontrib_verilog_diagrams.py
+++ b/sphinxcontrib_verilog_diagrams.py
@@ -218,7 +218,7 @@ 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)