diff --git a/Makefile b/Makefile
index 21d11434c..36e9d0aea 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,7 @@
 .PHONY: deps_table_update modified_only_fixup extra_quality_checks quality style fixup fix-copies test test-examples docs
 
+# make sure to test the local checkout in scripts and not the pre-installed one (don't use quotes!)
+export PYTHONPATH = src
 
 check_dirs := examples tests src utils