diff --git a/include/wx/msw/private/webrequest_winhttp.h b/include/wx/msw/private/webrequest_winhttp.h
index 044da9a9e5..11f2755528 100644
--- a/include/wx/msw/private/webrequest_winhttp.h
+++ b/include/wx/msw/private/webrequest_winhttp.h
@@ -24,7 +24,7 @@ class wxWebResponseWinHTTP : public wxWebResponseImpl
 public:
     wxWebResponseWinHTTP(wxWebRequestWinHTTP& request);
 
-    wxInt64 GetContentLength() const wxOVERRIDE { return m_contentLength; }
+    wxFileOffset GetContentLength() const wxOVERRIDE { return m_contentLength; }
 
     wxString GetURL() const wxOVERRIDE;
 
@@ -40,7 +40,7 @@ public:
 
 private:
     HINTERNET m_requestHandle;
-    wxInt64 m_contentLength;
+    wxFileOffset m_contentLength;
 
     wxDECLARE_NO_COPY_CLASS(wxWebResponseWinHTTP);
 };
diff --git a/include/wx/osx/private/webrequest_urlsession.h b/include/wx/osx/private/webrequest_urlsession.h
index 770b42d305..bea7502b96 100644
--- a/include/wx/osx/private/webrequest_urlsession.h
+++ b/include/wx/osx/private/webrequest_urlsession.h
@@ -29,7 +29,7 @@ public:
 
     ~wxWebResponseURLSession();
 
-    wxInt64 GetContentLength() const wxOVERRIDE;
+    wxFileOffset GetContentLength() const wxOVERRIDE;
 
     wxString GetURL() const wxOVERRIDE;
 
diff --git a/include/wx/private/webrequest.h b/include/wx/private/webrequest.h
index 4a515daa02..fc0848472a 100644
--- a/include/wx/private/webrequest.h
+++ b/include/wx/private/webrequest.h
@@ -133,7 +133,7 @@ class wxWebResponseImpl : public wxRefCounterMT
 public:
     virtual ~wxWebResponseImpl();
 
-    virtual wxInt64 GetContentLength() const = 0;
+    virtual wxFileOffset GetContentLength() const = 0;
 
     virtual wxString GetURL() const = 0;
 
diff --git a/include/wx/private/webrequest_curl.h b/include/wx/private/webrequest_curl.h
index 93e38b439c..47c13f43e1 100644
--- a/include/wx/private/webrequest_curl.h
+++ b/include/wx/private/webrequest_curl.h
@@ -95,7 +95,7 @@ class wxWebResponseCURL : public wxWebResponseImpl
 public:
     explicit wxWebResponseCURL(wxWebRequestCURL& request);
 
-    wxInt64 GetContentLength() const wxOVERRIDE;
+    wxFileOffset GetContentLength() const wxOVERRIDE;
 
     wxString GetURL() const wxOVERRIDE;
 
diff --git a/include/wx/webrequest.h b/include/wx/webrequest.h
index 2f9ffb51e1..f73fe75040 100644
--- a/include/wx/webrequest.h
+++ b/include/wx/webrequest.h
@@ -93,7 +93,7 @@ public:
 
     bool IsOk() const { return m_impl.get() != NULL; }
 
-    wxInt64 GetContentLength() const;
+    wxFileOffset GetContentLength() const;
 
     wxString GetURL() const;
 
diff --git a/interface/wx/webrequest.h b/interface/wx/webrequest.h
index db900dabb7..fbee289ab8 100644
--- a/interface/wx/webrequest.h
+++ b/interface/wx/webrequest.h
@@ -394,6 +394,8 @@ public:
 
         This value is based on the @c Content-Length header, if none is found
         it will return -1.
+
+        @see wxWebResponse::GetContentLength()
     */
     wxFileOffset GetBytesExpectedToReceive() const;
     ///@}
@@ -515,6 +517,14 @@ public:
     */
     wxString GetHeader(const wxString& name) const;
 
+    /**
+        Get the length of returned data if available.
+
+        Returns the value specified in the @c Content-Length: response header
+        of @c -1 if not available.
+     */
+    wxFileOffset GetContentLength() const;
+
     /**
         Returns the MIME type of the response (if available).
     */
diff --git a/src/common/webrequest.cpp b/src/common/webrequest.cpp
index d1d51d2662..831418a9b5 100644
--- a/src/common/webrequest.cpp
+++ b/src/common/webrequest.cpp
@@ -677,7 +677,7 @@ wxWebResponse::~wxWebResponse()
 {
 }
 
-wxInt64 wxWebResponse::GetContentLength() const
+wxFileOffset wxWebResponse::GetContentLength() const
 {
     wxCHECK_IMPL( -1 );
 
diff --git a/src/common/webrequest_curl.cpp b/src/common/webrequest_curl.cpp
index ab1cfceb77..71a11b7e90 100644
--- a/src/common/webrequest_curl.cpp
+++ b/src/common/webrequest_curl.cpp
@@ -99,7 +99,7 @@ size_t wxWebResponseCURL::CURLOnHeader(const char * buffer, size_t size)
     return size;
 }
 
-wxInt64 wxWebResponseCURL::GetContentLength() const
+wxFileOffset wxWebResponseCURL::GetContentLength() const
 {
 #if CURL_AT_LEAST_VERSION(7, 55, 0)
     curl_off_t len = 0;
@@ -108,7 +108,7 @@ wxInt64 wxWebResponseCURL::GetContentLength() const
 #else
     double len = 0;
     curl_easy_getinfo(GetHandle(), CURLINFO_CONTENT_LENGTH_DOWNLOAD, &len);
-    return (wxInt64)len;
+    return (wxFileOffset)len;
 #endif
 }
 
diff --git a/src/osx/webrequest_urlsession.mm b/src/osx/webrequest_urlsession.mm
index 289b8f1b92..917cb1b862 100644
--- a/src/osx/webrequest_urlsession.mm
+++ b/src/osx/webrequest_urlsession.mm
@@ -209,7 +209,7 @@ void wxWebResponseURLSession::HandleData(WX_NSData data)
     ReportDataReceived(data.length);
 }
 
-wxInt64 wxWebResponseURLSession::GetContentLength() const
+wxFileOffset wxWebResponseURLSession::GetContentLength() const
 {
     return m_task.response.expectedContentLength;
 }