Index: build/ac-macros/swig.m4
===================================================================
--- build/ac-macros/swig.m4	(revision 1868603)
+++ build/ac-macros/swig.m4	(working copy)
@@ -157,10 +157,18 @@
                ac_cv_python_is_py3="yes"
           ])
 
-          if test "$ac_cv_python_is_py3" = "yes"; then
-             SWIG_PY_OPTS="-python -py3"
+          if test "$SWIG_VERSION" -ge "400000"; then
+            if test "$ac_cv_python_is_py3" = "yes"; then
+              SWIG_PY_OPTS="-python -py3 -nofastunpack"
+            else
+               SWIG_PY_OPTS="-python -nofastunpack"
+            fi
           else
-             SWIG_PY_OPTS="-python -classic"
+            if test "$ac_cv_python_is_py3" = "yes"; then
+              SWIG_PY_OPTS="-python -py3"
+            else
+               SWIG_PY_OPTS="-python -classic"
+            fi
           fi
 
           dnl SWIG Python bindings successfully configured, clear the error message