diff --git a/Misc/build.sh b/Misc/build.sh
index efbad56..0c8d4d5 100755
--- a/Misc/build.sh
+++ b/Misc/build.sh
@@ -59,7 +59,7 @@
 PYTHON=$INSTALL_DIR/bin/python
 
 # Python options and regression test program that should always be run.
-REGRTEST_ARGS="-E $INSTALL_DIR/lib/python3.0/test/regrtest.py"
+REGRTEST_ARGS="-E -tt $INSTALL_DIR/lib/python3.0/test/regrtest.py"
 
 REFLOG="build/reflog.txt.out"
 # These tests are not stable and falsely report leaks sometimes.