diff --git a/cmake/GtsamCythonWrap.cmake b/cmake/GtsamCythonWrap.cmake
index a8793a4a9..7f98356d3 100644
--- a/cmake/GtsamCythonWrap.cmake
+++ b/cmake/GtsamCythonWrap.cmake
@@ -127,7 +127,9 @@ function(wrap_library_cython interface_header generated_files_path extra_imports
     VERBATIM
     WORKING_DIRECTORY ${generated_files_path}/../)
   add_custom_target(cython_wrap_${module_name}_pyx ALL DEPENDS ${generated_pyx})
-  add_dependencies(cython_wrap_${module_name}_pyx ${dependencies})
+  if(NOT ${dependencies} STREQUAL "")
+    add_dependencies(cython_wrap_${module_name}_pyx ${dependencies})
+  endif()
 
   message(STATUS "Cythonize and build ${module_name}.pyx")
   get_property(include_dirs DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY INCLUDE_DIRECTORIES)