diff --git a/cmake/modules/ExternalProject.cmake b/cmake/modules/ExternalProject.cmake
index d85ed8483ae607917577b300583acb95118d0e39..8e6ce3276f800ebaaabce167e466d31bc3eb4717 100644
--- a/cmake/modules/ExternalProject.cmake
+++ b/cmake/modules/ExternalProject.cmake
@@ -1161,7 +1161,7 @@ function(ExternalProject_Add_Step name step)
   if(command AND log)
     _ep_write_log_script(${name} ${step} command)
   endif()
-if(${work_dir})
+if(work_dir)
   add_custom_command(
     OUTPUT ${stamp_file}
     COMMENT ${comment}