diff --git a/netwerk/protocol/ftp/nsFTPChannel.cpp b/netwerk/protocol/ftp/nsFTPChannel.cpp
index e3de9ccb69ef..a4a2019f592b 100644
--- a/netwerk/protocol/ftp/nsFTPChannel.cpp
+++ b/netwerk/protocol/ftp/nsFTPChannel.cpp
@@ -6,7 +6,6 @@
 
 #include "nsFTPChannel.h"
 #include "nsFtpConnectionThread.h"  // defines nsFtpState
-#include "nsMimeTypes.h"
 
 #include "nsThreadUtils.h"
 #include "mozilla/Attributes.h"
@@ -92,7 +91,6 @@ nsresult nsFtpChannel::OpenContentStream(bool async, nsIInputStream** result,
                                          nsIChannel** channel) {
   if (!async) return NS_ERROR_NOT_IMPLEMENTED;
 
-  SetContentType(NS_LITERAL_CSTRING(APPLICATION_OCTET_STREAM));
   RefPtr<nsFtpState> state = new nsFtpState();
 
   nsresult rv = state->Init(this);
diff --git a/netwerk/protocol/ftp/nsFtpConnectionThread.cpp b/netwerk/protocol/ftp/nsFtpConnectionThread.cpp
index e421b509c322..f8dbc81d93dd 100644
--- a/netwerk/protocol/ftp/nsFtpConnectionThread.cpp
+++ b/netwerk/protocol/ftp/nsFtpConnectionThread.cpp
@@ -1101,6 +1101,8 @@ nsFtpState::R_retr() {
   }
 
   if (mResponseCode / 100 == 1) {
+    mChannel->SetContentType(NS_LITERAL_CSTRING(APPLICATION_OCTET_STREAM));
+
     Telemetry::ScalarAdd(
         Telemetry::ScalarID::NETWORKING_FTP_OPENED_CHANNELS_FILES, 1);