diff --git a/include/wx/sstream.h b/include/wx/sstream.h
index 19f37c58d3..f24419f8ad 100644
--- a/include/wx/sstream.h
+++ b/include/wx/sstream.h
@@ -63,15 +63,7 @@ public:
     // Note that the conversion object should have the life time greater than
     // this stream.
     wxStringOutputStream(wxString *pString = NULL,
-                         wxMBConv& conv = wxConvUTF8)
-        : m_conv(conv)
-#if wxUSE_UNICODE
-        , m_unconv(0)
-#endif // wxUSE_UNICODE
-    {
-        m_str = pString ? pString : &m_strInternal;
-        m_pos = m_str->length() / sizeof(wxChar);
-    }
+                         wxMBConv& conv = wxConvUTF8);
 
     // get the string containing current output
     const wxString& GetString() const { return *m_str; }
diff --git a/src/common/sstream.cpp b/src/common/sstream.cpp
index 009e2c04b6..1ed54f5c9d 100644
--- a/src/common/sstream.cpp
+++ b/src/common/sstream.cpp
@@ -128,6 +128,16 @@ size_t wxStringInputStream::OnSysRead(void *buffer, size_t size)
 // wxStringOutputStream implementation
 // ============================================================================
 
+wxStringOutputStream::wxStringOutputStream(wxString *pString, wxMBConv& conv)
+    : m_conv(conv)
+#if wxUSE_UNICODE
+    , m_unconv(0)
+#endif // wxUSE_UNICODE
+{
+    m_str = pString ? pString : &m_strInternal;
+    m_pos = m_str->length() / sizeof(wxChar);
+}
+
 // ----------------------------------------------------------------------------
 // seek/tell
 // ----------------------------------------------------------------------------