diff --git a/Makefile.pre.in b/Makefile.pre.in
index e20946cf993..80cb42e6637 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -706,7 +706,7 @@ $(LIBRARY_OBJS) $(MODOBJS) Modules/python.o: $(PYTHON_HEADERS)
 
 TESTOPTS=	-l $(EXTRATESTOPTS)
 TESTPROG=	$(srcdir)/Lib/test/regrtest.py
-TESTPYTHON=	$(RUNSHARED) ./$(BUILDPYTHON) -E -bb
+TESTPYTHON=	$(RUNSHARED) ./$(BUILDPYTHON) -Wd -E -bb
 test:		all platform
 		-find $(srcdir)/Lib -name '*.py[co]' -print | xargs rm -f
 		-$(TESTPYTHON) $(TESTPROG) $(TESTOPTS)
diff --git a/PCbuild/rt.bat b/PCbuild/rt.bat
index 1ce0107f0a5..109d4b663ed 100644
--- a/PCbuild/rt.bat
+++ b/PCbuild/rt.bat
@@ -40,7 +40,7 @@ if "%1"=="-x64" (set prefix=amd64) & (set tcltk=tcltk64) & shift & goto CheckOpt
 
 PATH %PATH%;..\..\%tcltk%\bin
 set exe=%prefix%\python%suffix%
-set cmd=%exe% %dashO% -E ../lib/test/regrtest.py %1 %2 %3 %4 %5 %6 %7 %8 %9
+set cmd=%exe% %dashO% -Wd -E ../lib/test/regrtest.py %1 %2 %3 %4 %5 %6 %7 %8 %9
 if defined qmode goto Qmode
 
 echo Deleting .pyc/.pyo files ...