diff --git a/tools/proving-v1/pc2-chain.ps1 b/tools/proving-v1/pc2-chain.ps1
index a56be84e2..cbb8992e6 100644
--- a/tools/proving-v1/pc2-chain.ps1
+++ b/tools/proving-v1/pc2-chain.ps1
@@ -26,10 +26,12 @@ $first = $tip - 30; $last = $first + 7
 $t = Get-Date
 $body = (@{jsonrpc='2.0'; id=1; method='igneum_exportSegments'; params=@('0x0', ('0x{0:x}' -f $last))} | ConvertTo-Json -Compress)
 $seqFile = Join-Path $job 'seq.json'
-try {
-  $resp = Invoke-WebRequest -Method Post -Uri "http://127.0.0.1:$evmPort" -ContentType 'application/json' -Body $body -TimeoutSec 600 -UseBasicParsing
-  [IO.File]::WriteAllBytes($seqFile, $resp.Content)
-} catch { "RESULT export FAILED: $_"; exit 1 }
+$bodyFile = Join-Path $job 'export-request.json'
+[IO.File]::WriteAllText($bodyFile, $body, (New-Object System.Text.UTF8Encoding $false))
+# curl.exe (Windows 10+ ships it) streams the 70 MB reply to a file; Invoke-WebRequest's Content is a string there
+# and WriteAllBytes refused it (the first run, 19:52Z)
+& curl.exe -s -S -m 600 -X POST "http://127.0.0.1:$evmPort" -H 'Content-Type: application/json' --data-binary "@$bodyFile" -o $seqFile 2>&1 | ForEach-Object { "curl: $_" }
+if (-not (Test-Path $seqFile) -or (Get-Item $seqFile).Length -lt 1000) { "RESULT export FAILED: no reply file"; exit 1 }
 $len = (Get-Item $seqFile).Length
 "RESULT export $(Stamp) $len bytes in $([math]::Round(((Get-Date) - $t).TotalSeconds,1)) s to $seqFile"
 # the JSON-RPC envelope: the exporter wants the result object; unwrap with python inside WSL (below)