diff --git a/pkg/client/client.go b/pkg/client/client.go
index 679b1fda3..d2a8647da 100644
--- a/pkg/client/client.go
+++ b/pkg/client/client.go
@@ -716,6 +716,10 @@ func (c *Client) GetRecentPermanodes(ctx context.Context, req *search.RecentRequ
 	return res, nil
 }
 
+// GetPermanodesWithAttr searches for permanodes that match the given search request.
+// The Fuzzy option in the request must not be set, and the Attribute option
+// must be set.
+// Only indexed attributes may be queried.
 func (c *Client) GetPermanodesWithAttr(ctx context.Context, req *search.WithAttrRequest) (*search.WithAttrResponse, error) {
 	sr, err := c.SearchRoot()
 	if err != nil {
diff --git a/pkg/index/index.go b/pkg/index/index.go
index f160bb63c..e088c0cd4 100644
--- a/pkg/index/index.go
+++ b/pkg/index/index.go
@@ -1031,6 +1031,9 @@ func (x *Index) SearchPermanodesWithAttr(ctx context.Context, dest chan<- blob.R
 	if request.Attribute == "" {
 		return errors.New("index: missing Attribute in SearchPermanodesWithAttr")
 	}
+	if !IsIndexedAttribute(request.Attribute) {
+		return fmt.Errorf("SearchPermanodesWithAttr: called with a non-indexed attribute %q", request.Attribute)
+	}
 
 	keyId, err := x.KeyId(ctx, request.Signer)
 	if err == sorted.ErrNotFound {
diff --git a/pkg/index/indextest/tests.go b/pkg/index/indextest/tests.go
index 73876971a..2c048f7f8 100644
--- a/pkg/index/indextest/tests.go
+++ b/pkg/index/indextest/tests.go
@@ -317,6 +317,7 @@ func Index(t *testing.T, initIdx func() *index.Index) {
 	t.Logf("set attribute %q", rootClaim)
 
 	pnChild := id.NewPermanode()
+	id.SetAttribute(pnChild, "unindexed", "lost in time and space")
 	br3 := id.SetAttribute(pnChild, "tag", "bar")
 	br3Time := id.LastTime()
 	t.Logf("set attribute %q", br3)
@@ -536,6 +537,50 @@ func Index(t *testing.T, initIdx func() *index.Index) {
 		}
 	}
 
+	// SearchPermanodesWithAttr - match none with attr type "tag=nosuchtag"
+	{
+		ch := make(chan blob.Ref, 10)
+		req := &camtypes.PermanodeByAttrRequest{
+			Signer:    id.SignerBlobRef,
+			Attribute: "tag",
+			Query:     "nosuchtag",
+		}
+		err := id.Index.SearchPermanodesWithAttr(ctx, ch, req)
+		if err != nil {
+			t.Fatalf("SearchPermanodesWithAttr = %v", err)
+		}
+		var got []blob.Ref
+		for r := range ch {
+			got = append(got, r)
+		}
+		want := []blob.Ref{}
+		if len(got) != len(want) {
+			t.Errorf("SearchPermanodesWithAttr results differ.\n got: %q\nwant: %q",
+				got, want)
+		}
+	}
+	// SearchPermanodesWithAttr - error for unindexed attr
+	{
+		ch := make(chan blob.Ref, 10)
+		req := &camtypes.PermanodeByAttrRequest{
+			Signer:    id.SignerBlobRef,
+			Attribute: "unindexed",
+		}
+		err := id.Index.SearchPermanodesWithAttr(ctx, ch, req)
+		if err != nil {
+			t.Fatalf("SearchPermanodesWithAttr = %v", err)
+		}
+		var got []blob.Ref
+		for r := range ch {
+			got = append(got, r)
+		}
+		want := []blob.Ref{}
+		if len(got) != len(want) {
+			t.Errorf("SearchPermanodesWithAttr results differ.\n got: %q\nwant: %q",
+				got, want)
+		}
+	}
+
 	// Delete value "pony" of type "title" (which does not actually exist) for pn
 	br4 := id.DelAttribute(pn, "title", "pony")
 	br4Time := id.LastTime()