diff --git a/tools/install_prereqs.sh b/tools/install_prereqs.sh
index f2d57c8..bb470b2 100755
--- a/tools/install_prereqs.sh
+++ b/tools/install_prereqs.sh
@@ -79,6 +79,8 @@
     fi
 fi
 
+# TODO(clarkb) remove these once we are switched to global venv by default
+export PYTHON=$(which python${PYTHON3_VERSION} 2>/dev/null || which python3 2>/dev/null)
 
 # Mark end of run
 # ---------------