diff --git a/doc/CMakeLists.txt b/doc/CMakeLists.txt
index df3e9b1e..e12849db 100644
--- a/doc/CMakeLists.txt
+++ b/doc/CMakeLists.txt
@@ -6,7 +6,7 @@ endif ()
 
 add_custom_target(doc
   COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/build.py ${FMT_VERSION}
-  SOURCES build.py conf.py _templates/layout.html)
+  SOURCES api.rst build.py conf.py _templates/layout.html)
 
 install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/html/
         DESTINATION share/doc/fmt OPTIONAL)