diff --git a/doc/conf.py.in b/doc/conf.py.in
index 927a0b9a..eef3fb3d 100644
--- a/doc/conf.py.in
+++ b/doc/conf.py.in
@@ -2,6 +2,9 @@
 #
 # TRIQS documentation build configuration file
 
+import sys
+sys.path.insert(0, "@TRIQS_SPHINXEXT_PATH@/numpydoc")
+
 extensions = ['sphinx.ext.autodoc',
               'sphinx.ext.mathjax',
               'sphinx.ext.intersphinx',