diff --git a/dlls/mshtml/nsiface.idl b/dlls/mshtml/nsiface.idl
index 8973701bd63..8a359d9c203 100644
--- a/dlls/mshtml/nsiface.idl
+++ b/dlls/mshtml/nsiface.idl
@@ -46,7 +46,6 @@ typedef WCHAR PRUnichar;
 typedef ULONG PRUint32;
 typedef WORD PRUint16;
 typedef BYTE PRUint8;
-typedef LONGLONG PRInt64;
 typedef ULONGLONG PRUint64;
 
 /*
@@ -56,7 +55,7 @@ typedef ULONGLONG PRUint64;
  */
 #define int16_t short
 #define int32_t LONG
-#define int64_t PRInt64
+#define int64_t INT64
 
 #define uint8_t PRUint8
 #define uint16_t PRUint16
diff --git a/dlls/mshtml/nsio.c b/dlls/mshtml/nsio.c
index af5775010d9..9e35921406b 100644
--- a/dlls/mshtml/nsio.c
+++ b/dlls/mshtml/nsio.c
@@ -1463,7 +1463,7 @@ static nsrefcnt NSAPI nsUploadChannel_Release(nsIUploadChannel *iface)
 }
 
 static nsresult NSAPI nsUploadChannel_SetUploadStream(nsIUploadChannel *iface,
-        nsIInputStream *aStream, const nsACString *aContentType, PRInt64 aContentLength)
+        nsIInputStream *aStream, const nsACString *aContentType, INT64 aContentLength)
 {
     nsChannel *This = impl_from_nsIUploadChannel(iface);
     const char *content_type;