1 files changed, 9 insertions, 1 deletions
diff --git a/deps/undici/src/lib/fetch/body.js b/deps/undici/src/lib/fetch/body.js
index c291afa936..db450ee6bd 100644
--- a/deps/undici/src/lib/fetch/body.js
+++ b/deps/undici/src/lib/fetch/body.js
@@ -123,6 +123,7 @@ function extractBody (object, keepalive = false) {
     const blobParts = []
     const rn = new Uint8Array([13, 10]) // '\r\n'
     length = 0
+    let hasUnknownSizeValue = false
 
     for (const [name, value] of object) {
       if (typeof value === 'string') {
@@ -138,13 +139,20 @@ function extractBody (object, keepalive = false) {
             value.type || 'application/octet-stream'
           }\r\n\r\n`)
         blobParts.push(chunk, value, rn)
-        length += chunk.byteLength + value.size + rn.byteLength
+        if (typeof value.size === 'number') {
+          length += chunk.byteLength + value.size + rn.byteLength
+        } else {
+          hasUnknownSizeValue = true
+        }
       }
     }
 
     const chunk = enc.encode(`--${boundary}--`)
     blobParts.push(chunk)
     length += chunk.byteLength
+    if (hasUnknownSizeValue) {
+      length = null
+    }
 
     // Set source to object.
     source = object