diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index 5d9a140fec49..bf65f731ba88 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -101,6 +101,7 @@
 #include "nsICookieService.h"
 #include "nsIConsoleReportCollector.h"
 #include "nsObjectLoadingContent.h"
+#include "nsStringStream.h"
 
 // we want to explore making the document own the load group
 // so we can associate the document URI with the load group.
@@ -622,8 +623,8 @@ SendPing(void* aClosure, nsIContent* aContent, nsIURI* aURI,
   NS_NAMED_LITERAL_CSTRING(uploadData, "PING");
 
   nsCOMPtr<nsIInputStream> uploadStream;
-  NS_NewPostDataStream(getter_AddRefs(uploadStream), false, uploadData);
-  if (!uploadStream) {
+  rv = NS_NewCStringInputStream(getter_AddRefs(uploadStream), uploadData);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
     return;
   }
 
diff --git a/netwerk/base/nsNetUtil.cpp b/netwerk/base/nsNetUtil.cpp
index bfda815f76b0..aa2e9b6eaf0f 100644
--- a/netwerk/base/nsNetUtil.cpp
+++ b/netwerk/base/nsNetUtil.cpp
@@ -1359,43 +1359,6 @@ NS_NewBufferedInputStream(nsIInputStream** aResult,
     return rv;
 }
 
-nsresult
-NS_NewPostDataStream(nsIInputStream  **result,
-                     bool              isFile,
-                     const nsACString &data)
-{
-    nsresult rv;
-
-    if (isFile) {
-        nsCOMPtr<nsIFile> file;
-        nsCOMPtr<nsIInputStream> fileStream;
-
-        rv = NS_NewNativeLocalFile(data, false, getter_AddRefs(file));
-        if (NS_SUCCEEDED(rv)) {
-            rv = NS_NewLocalFileInputStream(getter_AddRefs(fileStream), file);
-            if (NS_SUCCEEDED(rv)) {
-                // wrap the file stream with a buffered input stream
-                rv = NS_NewBufferedInputStream(result, fileStream.forget(),
-                                               8192);
-            }
-        }
-        return rv;
-    }
-
-    // otherwise, create a string stream for the data (copies)
-    nsCOMPtr<nsIStringInputStream> stream
-        (do_CreateInstance("@mozilla.org/io/string-input-stream;1", &rv));
-    if (NS_FAILED(rv))
-        return rv;
-
-    rv = stream->SetData(data.BeginReading(), data.Length());
-    if (NS_FAILED(rv))
-        return rv;
-
-    stream.forget(result);
-    return NS_OK;
-}
-
 namespace {
 
 #define BUFFER_SIZE 4096
diff --git a/netwerk/base/nsNetUtil.h b/netwerk/base/nsNetUtil.h
index 44b3c6baeb28..ccfd9d681f2f 100644
--- a/netwerk/base/nsNetUtil.h
+++ b/netwerk/base/nsNetUtil.h
@@ -510,11 +510,6 @@ nsresult NS_NewBufferedOutputStream(nsIOutputStream** aResult,
                                     already_AddRefed<nsIOutputStream> aOutputStream,
                                     uint32_t aBufferSize);
 
-// returns an input stream compatible with nsIUploadChannel::SetUploadStream()
-nsresult NS_NewPostDataStream(nsIInputStream  **result,
-                              bool              isFile,
-                              const nsACString &data);
-
 /**
  * This function reads an inputStream and stores its content into a buffer. In
  * general, you should avoid using this function because, it blocks the current
diff --git a/security/manager/ssl/nsNSSCallbacks.cpp b/security/manager/ssl/nsNSSCallbacks.cpp
index c0e355a37bc8..36f9b4821896 100644
--- a/security/manager/ssl/nsNSSCallbacks.cpp
+++ b/security/manager/ssl/nsNSSCallbacks.cpp
@@ -30,6 +30,7 @@
 #include "nsNetUtil.h"
 #include "nsProtectedAuthThread.h"
 #include "nsProxyRelease.h"
+#include "nsStringStream.h"
 #include "pkix/pkixtypes.h"
 #include "ssl.h"
 #include "sslproto.h"
@@ -140,9 +141,8 @@ nsHTTPDownloadEvent::Run()
   if (mRequestSession->mHasPostData)
   {
     nsCOMPtr<nsIInputStream> uploadStream;
-    rv = NS_NewPostDataStream(getter_AddRefs(uploadStream),
-                              false,
-                              mRequestSession->mPostData);
+    rv = NS_NewCStringInputStream(getter_AddRefs(uploadStream),
+                                  mRequestSession->mPostData);
     NS_ENSURE_SUCCESS(rv, rv);
 
     nsCOMPtr<nsIUploadChannel> uploadChannel(do_QueryInterface(chan));