diff --git a/frontends/PyCDE/integration_test/test_software/esi_test.py b/frontends/PyCDE/integration_test/test_software/esi_test.py
index c63e6b44ae..9b99314d46 100644
--- a/frontends/PyCDE/integration_test/test_software/esi_test.py
+++ b/frontends/PyCDE/integration_test/test_software/esi_test.py
@@ -10,7 +10,7 @@ data = mmio.read(8)
 print(f"mmio data@8: {data:X}")
 assert data == 0x207D98E5E5100E51
 
-assert acc.sysinfo().esi_version() == 1
+assert acc.sysinfo().esi_version() == 0
 m = acc.manifest()
 assert m.api_version == 0
 print(m.type_table)
diff --git a/integration_test/Dialect/ESI/runtime/loopback.mlir.py b/integration_test/Dialect/ESI/runtime/loopback.mlir.py
index 9c91e169b9..cb24c46766 100644
--- a/integration_test/Dialect/ESI/runtime/loopback.mlir.py
+++ b/integration_test/Dialect/ESI/runtime/loopback.mlir.py
@@ -7,7 +7,7 @@ import time
 platform = sys.argv[1]
 acc = esiaccel.AcceleratorConnection(platform, sys.argv[2])
 
-assert acc.sysinfo().esi_version() == 1
+assert acc.sysinfo().esi_version() == 0
 m = acc.manifest()
 assert m.api_version == 0
 
diff --git a/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Manifest.sv b/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Manifest.sv
index 30b41b7d53..7468d4d6e5 100644
--- a/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Manifest.sv
+++ b/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Manifest.sv
@@ -16,7 +16,7 @@ import Cosim_DpiPkg::*;
 module Cosim_Manifest
 #(
   parameter int COMPRESSED_MANIFEST_SIZE = 0,
-  parameter int unsigned ESI_VERSION = 1
+  parameter int unsigned ESI_VERSION = 0
 )(
   input logic [COMPRESSED_MANIFEST_SIZE-1:0][7:0] compressed_manifest
 );
diff --git a/lib/Dialect/ESI/runtime/cpp/lib/backends/Trace.cpp b/lib/Dialect/ESI/runtime/cpp/lib/backends/Trace.cpp
index d9a4f2a1e3..f4ba07dc2d 100644
--- a/lib/Dialect/ESI/runtime/cpp/lib/backends/Trace.cpp
+++ b/lib/Dialect/ESI/runtime/cpp/lib/backends/Trace.cpp
@@ -28,8 +28,8 @@ using namespace esi;
 using namespace esi::services;
 using namespace esi::backends::trace;
 
-// We only support v1.
-constexpr uint32_t ESIVersion = 1;
+// We only support v0.
+constexpr uint32_t ESIVersion = 0;
 
 namespace {
 class TraceChannelPort;