diff --git a/Makefile b/Makefile
index 72e08770f9..96a1da6d8b 100644
--- a/Makefile
+++ b/Makefile
@@ -41,7 +41,7 @@ help:
 #        treated as errors, which is good to skip simple Sphinx syntax mistakes.
 .PHONY: build
 build: setup
-		PYTHONWARNINGS=ignore::FutureWarning sphinx-build -j auto -W --keep-going -b html -d $(OUTPUT_DOCTREE) -D language=$(LANGUAGE) . $(OUTPUT_HTML)
+		PYTHONWARNINGS=ignore::FutureWarning $(VENV)/bin/sphinx-build -j auto -W --keep-going -b html -d $(OUTPUT_DOCTREE) -D language=$(LANGUAGE) . $(OUTPUT_HTML)
 		@echo "Success! Open file://`pwd`/$(OUTPUT_HTML)/index.html, " \
 					"or run 'make serve' to see them in http://localhost:8000";