diff --git i/Makefile.in w/Makefile.in
index d039ed3e9d6a..c40e6eac56ae 100644
--- i/Makefile.in
+++ w/Makefile.in
@@ -493,7 +493,7 @@ AUTOMAKE_OPTIONS = 1.5 check-news dist-bzip2 -Wno-portability \
 
 PYTHONPATH1 = $(abs_top_srcdir)/python-pkg/lirc:
 PYTHONPATH2 = $(abs_top_srcdir)/python-pkg/lirc/lib/.libs
-PYTHONPATH = $(PYTHONPATH1):$(PYTHONPATH2)
+PYTHONPATH := $(PYTHONPATH):$(PYTHONPATH1):$(PYTHONPATH2)
 PYLINT = python3-pylint
 pylint_template = {path}:{line}: [{msg_id}({symbol}), {obj}] {msg}
 GIT_COMMIT = $(shell git log -1 --pretty=format:%h || echo UNKNOWN)