diff --git a/doc/requirements.txt b/doc/requirements.txt
deleted file mode 100644
index ef36add..0000000
--- a/doc/requirements.txt
+++ /dev/null
@@ -1 +0,0 @@
-sphinxcontrib-bibtex
diff --git a/setup.cfg b/setup.cfg
index a84acf1..8cb44ed 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -37,6 +37,10 @@ console_scripts =
     pylems = lems.run:main
 
 
+[options.extras_require]
+doc =
+    sphinxcontrib-bibtex
+
 [flake8]
 # ignore:
 # spacing around operators, comment blocks, in argument lists