diff --git a/Sources/Apollo/URLSessionClient.swift b/Sources/Apollo/URLSessionClient.swift
index 5f10bc532b..0367c3324b 100644
--- a/Sources/Apollo/URLSessionClient.swift
+++ b/Sources/Apollo/URLSessionClient.swift
@@ -298,7 +298,7 @@ open class URLSessionClient: NSObject, URLSessionDelegate, URLSessionTaskDelegat
         return
       }
 
-      let boundaryMarker = "--\(boundaryString)"
+      let boundaryMarker = "\r\n--\(boundaryString)\r\n"
       guard
         let dataString = String(data: taskData.data, encoding: .utf8)?.trimmingCharacters(in: .newlines),
         let lastBoundaryIndex = dataString.range(of: boundaryMarker, options: .backwards)?.upperBound,