Index: cmake/modules/AddSphinxTarget.cmake
===================================================================
--- cmake/modules/AddSphinxTarget.cmake
+++ cmake/modules/AddSphinxTarget.cmake
@@ -14,6 +14,11 @@
   else()
     set(SPHINX_WARNINGS_AS_ERRORS_FLAG "")
   endif()
+  if (SPHINX_WARN_MISSING_REFERENCES)
+    set(SPHINX_WARN_MISSING_REFERENCES_FLAG "-n")
+  else()
+    set(SPHINX_WARN_MISSING_REFERENCES_FLAG "")
+  endif()
 
   add_custom_target(${SPHINX_TARGET_NAME}
                     COMMAND ${SPHINX_EXECUTABLE}
@@ -21,6 +26,7 @@
                             -d "${SPHINX_DOC_TREE_DIR}"
                             -q # Quiet: no output other than errors and warnings.
                             ${SPHINX_WARNINGS_AS_ERRORS_FLAG} # Treat warnings as errors if requested
+			    ${SPHINX_WARN_MISSING_REFERENCES_FLAG} # Treat missing references as warnings
                             "${CMAKE_CURRENT_SOURCE_DIR}" # Source
                             "${SPHINX_BUILD_DIR}" # Output
                     COMMENT