diff --git a/entc/gen/type.go b/entc/gen/type.go
index a0733f721..4c57c770f 100644
--- a/entc/gen/type.go
+++ b/entc/gen/type.go
@@ -619,14 +619,10 @@ func (t *Type) AddIndex(idx *load.Index) error {
 	}
 	for _, name := range idx.Fields {
 		var f *Field
-		if name == t.ID.Name {
+		if t.HasOneFieldID() && name == t.ID.Name {
 			f = t.ID
-		} else {
-			var ok bool
-			f, ok = t.fields[name]
-			if !ok {
-				return fmt.Errorf("unknown index field %q", name)
-			}
+		} else if f = t.fields[name]; f == nil {
+			return fmt.Errorf("unknown index field %q", name)
 		}
 		index.Columns = append(index.Columns, f.StorageKey())
 	}
@@ -640,7 +636,7 @@ func (t *Type) AddIndex(idx *load.Index) error {
 		}
 		switch {
 		case ed == nil:
-			return fmt.Errorf("unknown index field %q", name)
+			return fmt.Errorf("unknown index edge %q", name)
 		case ed.Rel.Type == O2O && !ed.IsInverse():
 			return fmt.Errorf("non-inverse edge (edge.From) for index %q on O2O relation", name)
 		case ed.Rel.Type != M2O && ed.Rel.Type != O2O:
diff --git a/entc/integration/edgeschema/ent/migrate/schema.go b/entc/integration/edgeschema/ent/migrate/schema.go
index a84191d86..f707f3f83 100644
--- a/entc/integration/edgeschema/ent/migrate/schema.go
+++ b/entc/integration/edgeschema/ent/migrate/schema.go
@@ -41,6 +41,11 @@ var (
 				Unique:  true,
 				Columns: []*schema.Column{FriendshipsColumns[3], FriendshipsColumns[4]},
 			},
+			{
+				Name:    "friendship_created_at",
+				Unique:  false,
+				Columns: []*schema.Column{FriendshipsColumns[2]},
+			},
 		},
 	}
 	// GroupsColumns holds the columns for the "groups" table.
@@ -79,6 +84,13 @@ var (
 				OnDelete:   schema.NoAction,
 			},
 		},
+		Indexes: []*schema.Index{
+			{
+				Name:    "relationship_weight",
+				Unique:  false,
+				Columns: []*schema.Column{RelationshipsColumns[0]},
+			},
+		},
 	}
 	// TweetsColumns holds the columns for the "tweets" table.
 	TweetsColumns = []*schema.Column{
diff --git a/entc/integration/edgeschema/ent/schema/friendship.go b/entc/integration/edgeschema/ent/schema/friendship.go
index 780af70d7..720ea0717 100644
--- a/entc/integration/edgeschema/ent/schema/friendship.go
+++ b/entc/integration/edgeschema/ent/schema/friendship.go
@@ -10,6 +10,7 @@ import (
 	"entgo.io/ent"
 	"entgo.io/ent/schema/edge"
 	"entgo.io/ent/schema/field"
+	"entgo.io/ent/schema/index"
 )
 
 // Friendship holds the edge schema definition of the Friendship relationship.
@@ -42,3 +43,10 @@ func (Friendship) Edges() []ent.Edge {
 			Field("friend_id"),
 	}
 }
+
+// Indexes of the Friendship.
+func (Friendship) Indexes() []ent.Index {
+	return []ent.Index{
+		index.Fields("created_at"),
+	}
+}
diff --git a/entc/integration/edgeschema/ent/schema/relationship.go b/entc/integration/edgeschema/ent/schema/relationship.go
index 3d4489571..a88fc9755 100644
--- a/entc/integration/edgeschema/ent/schema/relationship.go
+++ b/entc/integration/edgeschema/ent/schema/relationship.go
@@ -9,6 +9,7 @@ import (
 	"entgo.io/ent/schema"
 	"entgo.io/ent/schema/edge"
 	"entgo.io/ent/schema/field"
+	"entgo.io/ent/schema/index"
 )
 
 // Relationship holds the schema definition for the Relationship entity.
@@ -45,3 +46,10 @@ func (Relationship) Edges() []ent.Edge {
 			Field("relative_id"),
 	}
 }
+
+// Indexes of the Relationship.
+func (Relationship) Indexes() []ent.Index {
+	return []ent.Index{
+		index.Fields("weight"),
+	}
+}