diff --git a/hypopg_index.c b/hypopg_index.c
index 6ce9b2a..a1c31c3 100644
--- a/hypopg_index.c
+++ b/hypopg_index.c
@@ -632,7 +632,7 @@ hypo_index_store_parsetree(IndexStmt *node, const char *queryString)
 			}
 
 			/* get the opclass */
-			opclass = GetIndexOpClass(attribute->opclass,
+			opclass = ResolveOpClass(attribute->opclass,
 									  atttype,
 									  node->accessMethod,
 									  entry->relam);
diff --git a/import/hypopg_import_index.c b/import/hypopg_import_index.c
index 22d84db..7c58a02 100644
--- a/import/hypopg_import_index.c
+++ b/import/hypopg_import_index.c
@@ -100,6 +100,7 @@ build_index_tlist(PlannerInfo *root, IndexOptInfo *index,
 	return tlist;
 }
 
+#if PG_VERSION_NUM < 100000
 /*
  * Copied from src/backend/commands/indexcmds.c, not exported.
  * Resolve possibly-defaulted operator class specification
@@ -214,6 +215,7 @@ GetIndexOpClass(List *opclass, Oid attrType,
 
 	return opClassId;
 }
+#endif
 
 /*
  * Copied from src/backend/commands/indexcmds.c, not exported.
diff --git a/include/hypopg_import_index.h b/include/hypopg_import_index.h
index 4715771..0d28523 100644
--- a/include/hypopg_import_index.h
+++ b/include/hypopg_import_index.h
@@ -21,8 +21,11 @@
 
 extern List *build_index_tlist(PlannerInfo *root, IndexOptInfo *index,
 				  Relation heapRelation);
+#if PG_VERSION_NUM < 100000
 extern Oid GetIndexOpClass(List *opclass, Oid attrType,
 				char *accessMethodName, Oid accessMethodId);
+#define ResolveOpClass(o, at, acn, aci) GetIndexOpClass(o, at, acn, aci)
+#endif
 
 extern void CheckPredicate(Expr *predicate);
 extern bool CheckMutability(Expr *expr);