diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 398680a..153373e 100644
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
*************** init_custom_variable(const char *name,
*** 7607,7612 ****
--- 7607,7621 ----
  		elog(FATAL, "cannot create PGC_POSTMASTER variables after startup");
  
  	/*
+ 	 * We can't support custom GUC_LIST_QUOTE variables, because the wrong
+ 	 * things would happen if such a variable were set or pg_dump'd when the
+ 	 * defining extension isn't loaded.  Again, treat this as fatal because
+ 	 * the loadable module may be partly initialized already.
+ 	 */
+ 	if (flags & GUC_LIST_QUOTE)
+ 		elog(FATAL, "extensions cannot define GUC_LIST_QUOTE variables");
+ 
+ 	/*
  	 * Before pljava commit 398f3b876ed402bdaec8bc804f29e2be95c75139
  	 * (2015-12-15), two of that module's PGC_USERSET variables facilitated
  	 * trivial escalation to superuser privileges.  Restrict the variables to