diff --git a/Makefile.am b/Makefile.am
index a141cd5..173c7de 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,7 +1,8 @@
 EXTRA_DIST = CHANGES LICENSE README.rst
 SUBDIRS = doc src test
 
-check-local: html
+check-doc:
+	$(MAKE) SPHINXOPTS_EXTRA=-W html
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = jansson.pc
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 74a715c..1f2d855 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -3,7 +3,7 @@ EXTRA_DIST = conf.py apiref.rst changes.rst conformance.rst		\
 	ext/refcounting.py
 
 SPHINXBUILD = sphinx-build
-SPHINXOPTS = -d _build/doctrees -W
+SPHINXOPTS = -d _build/doctrees $(SPHINXOPTS_EXTRA)
 
 html-local:
 	$(SPHINXBUILD) -b html $(SPHINXOPTS) $(srcdir) _build/html