Index: Makefile.in
===================================================================
--- Makefile.in	(revision 1868599)
+++ Makefile.in	(working copy)
@@ -200,6 +200,7 @@
 SWIG_PY_FEATURES = @SWIG_PY_FEATURES@
 SWIG_PL_FEATURES = @SWIG_PL_FEATURES@
 SWIG_RB_FEATURES = @SWIG_RB_FEATURES@
+SWIG_PY_OPTS = @SWIG_PY_OPTS@
 
 COMPILE = $(CC) $(CMODEFLAGS) $(CPPFLAGS) $(CMAINTAINERFLAGS) $(CFLAGS) $(INCLUDES)
 COMPILE_NOWARN = $(CC) $(CMODEFLAGS) $(CPPFLAGS) $(CNOWARNFLAGS) $(CFLAGS) $(INCLUDES)
Index: build/ac-macros/swig.m4
===================================================================
--- build/ac-macros/swig.m4	(revision 1868599)
+++ build/ac-macros/swig.m4	(working copy)
@@ -128,6 +128,12 @@
       ac_cv_python_libs="`$PYTHON ${abs_srcdir}/build/get-py-info.py --libs`"
     ])
     SWIG_PY_LIBS="`SVN_REMOVE_STANDARD_LIB_DIRS($ac_cv_python_libs)`"
+
+    if test "$SWIG_VERSION" -ge "400000"; then
+      SWIG_PY_OPTS="-python -nofastunpack"
+    else
+      SWIG_PY_OPTS="-python -classic"
+    fi
   fi
 
   if test "$PERL" != "none"; then
@@ -270,6 +276,7 @@
   AC_SUBST(SWIG_PY_COMPILE)
   AC_SUBST(SWIG_PY_LINK)
   AC_SUBST(SWIG_PY_LIBS)
+  AC_SUBST(SWIG_PY_OPTS)
   AC_SUBST(SWIG_PL_INCLUDES)
   AC_SUBST(SWIG_PL_LINK)
   AC_SUBST(SWIG_RB_LINK)
Index: build.conf
===================================================================
--- build.conf	(revision 1868599)
+++ build.conf	(working copy)
@@ -101,7 +101,7 @@
 
 bdb-test-scripts =
 
-swig-python-opts = $(SWIG_FEATURES) -python $(SWIG_PY_FEATURES) -classic
+swig-python-opts = $(SWIG_FEATURES) $(SWIG_PY_OPTS) $(SWIG_PY_FEATURES)
 swig-perl-opts = $(SWIG_FEATURES) -perl $(SWIG_PL_FEATURES) -nopm -noproxy
 swig-ruby-opts = $(SWIG_FEATURES) -ruby $(SWIG_RB_FEATURES)
 swig-languages = python perl ruby