--- Makefile.pre.in
+++ Makefile.pre.in
@@ -57,7 +57,7 @@
 # Compiler options
 OPT=		@OPT@
 BASECFLAGS=	@BASECFLAGS@
-CFLAGS=		$(BASECFLAGS) $(OPT) $(EXTRA_CFLAGS)
+CFLAGS=		$(BASECFLAGS) $(OPT) -fwrapv $(EXTRA_CFLAGS)
 # Both CPPFLAGS and LDFLAGS need to contain the shell's value for setup.py to
 # be able to build extension modules using the directories specified in the
 # environment variables