diff --git a/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java b/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
index 595ec98efc..e5cca39bdf 100644
--- a/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
+++ b/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
@@ -592,18 +592,15 @@ public class QueryImpl implements Query {
                         OrderEntry e = list.get(i);
                         OrderingImpl o = orderings[i];
                         DynamicOperandImpl op = o.getOperand();
-                        if (!(op instanceof PropertyValueImpl)) {
-                            // ordered by a function: currently not supported
-                            canSortByIndex = false;
-                            break;
-                        }
                         // we only have one selector, so no need to check that
                         // TODO support joins
-                        String pn = ((PropertyValueImpl) op).getPropertyName();
-                        if (!pn.equals(e.getPropertyName())) {
-                            // ordered by another property
-                            canSortByIndex = false;
-                            break;
+                        if (op instanceof PropertyValueImpl) {
+                            String pn = ((PropertyValueImpl) op).getPropertyName();
+                            if (!pn.equals(e.getPropertyName())) {
+                                // ordered by another property
+                                canSortByIndex = false;
+                                break;
+                            }
                         }
                         if (o.isDescending() != (e.getOrder() == Order.DESCENDING)) {
                             // ordered ascending versus descending