diff --git a/Lib/distutils/command/build_ext.py b/Lib/distutils/command/build_ext.py
index 82474de..12d4083 100644
--- a/Lib/distutils/command/build_ext.py
+++ b/Lib/distutils/command/build_ext.py
@@ -533,7 +533,8 @@
         if self.swig_cpp:
             log.warn("--swig-cpp is deprecated - use --swig-opts=-c++")
 
-        if self.swig_cpp or ('-c++' in self.swig_opts):
+        if self.swig_cpp or ('-c++' in self.swig_opts) or \
+           ('-c++' in extension.swig_opts):
             target_ext = '.cpp'
         else:
             target_ext = '.c'
diff --git a/Misc/NEWS b/Misc/NEWS
index 0fdf4a1..96d427c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -209,6 +209,10 @@
 Library
 -------
 
+- Bug #1706381: Specifying the SWIG option "-c++" in the setup.py file
+  (as opposed to the command line) will now write file names ending in
+  ".cpp" too.
+
 - As specified in RFC 2616, an HTTP response like 2xx indicates that
   the client's request was successfully received, understood, and accepted.
   Now in these cases no error is raised in urllib2.