diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index d0e364e..c9386aa 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -26,6 +26,7 @@
 #ifdef CATCACHE_STATS
 #include "storage/ipc.h"		/* for on_proc_exit */
 #endif
+#include "storage/lmgr.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/inval.h"
@@ -967,8 +968,16 @@ InitCatCachePhase2(CatCache *cache, bool touch_index)
 	{
 		Relation	idesc;
 
+		/*
+		 * We must lock the underlying catalog before locking the index to
+		 * avoid deadlock, since RelationReloadIndexInfo might well need to
+		 * read the catalog, and if anyone else is exclusive-locking this
+		 * catalog and index they'll be doing it in that order.
+		 */
+		LockRelationOid(cache->cc_reloid, AccessShareLock);
 		idesc = index_open(cache->cc_indexoid, AccessShareLock);
 		index_close(idesc, AccessShareLock);
+		UnlockRelationOid(cache->cc_reloid, AccessShareLock);
 	}
 }