diff --git a/doc/CMakeLists.txt b/doc/CMakeLists.txt
index 40bbedc8..c131ac34 100644
--- a/doc/CMakeLists.txt
+++ b/doc/CMakeLists.txt
@@ -8,7 +8,7 @@ file(GLOB_RECURSE sources *.rst)
 
 set(sphinx_top ${CMAKE_CURRENT_BINARY_DIR}/html/contents.html)
 add_custom_command(OUTPUT ${sphinx_top} DEPENDS ${sources}
-  		   COMMAND ${TRIQS_SPHINXBUILD_EXECUTABLE} -c . -j8 -b html ${CMAKE_CURRENT_BINARY_DIR} html)
+		   COMMAND PYTHONPATH=${CMAKE_BINARY_DIR}/python:$ENV{PYTHONPATH} ${TRIQS_SPHINXBUILD_EXECUTABLE} -c . -j8 -b html ${CMAKE_CURRENT_BINARY_DIR} html)
 add_custom_target(docs_sphinx ALL DEPENDS ${sphinx_top} ${CMAKE_CURRENT_BINARY_DIR})
 
 # Application must be compiled first