diff --git a/Modules/ExternalProject/shared_internal_commands.cmake b/Modules/ExternalProject/shared_internal_commands.cmake
index db144541e5..acd97f19c8 100644
--- a/Modules/ExternalProject/shared_internal_commands.cmake
+++ b/Modules/ExternalProject/shared_internal_commands.cmake
@@ -1495,10 +1495,10 @@ function(_ep_add_update_command name)
       set(svn_interactive_args "--non-interactive")
     endif()
     set(svn_user_pw_args "")
-    if(DEFINED svn_username)
+    if(DEFINED _EP_SVN_USERNAME)
       set(svn_user_pw_args ${svn_user_pw_args} "--username=${svn_username}")
     endif()
-    if(DEFINED svn_password)
+    if(DEFINED _EP_SVN_PASSWORD)
       set(svn_user_pw_args ${svn_user_pw_args} "--password=${svn_password}")
     endif()
     if(svn_trust_cert)