diff --git a/core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/optimizer/BindingSetAssignmentInlinerOptimizer.java b/core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/optimizer/BindingSetAssignmentInlinerOptimizer.java
index 2d6c903d105..75350a62b69 100644
--- a/core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/optimizer/BindingSetAssignmentInlinerOptimizer.java
+++ b/core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/optimizer/BindingSetAssignmentInlinerOptimizer.java
@@ -72,6 +72,9 @@ public void meet(Filter node) throws RuntimeException {
 		public void meet(LeftJoin leftJoin) {
 			leftJoin.getLeftArg().visit(this);
 			// we can not pre-bind values for the optional part of the left-join
+
+			// in a left-join, we can pre-bind variables in the RHS _if_, after pre-binding in the LHS, those variables
+			// are now fixed.
 		}
 
 		@Override
diff --git a/core/queryparser/sparql/src/test/java/org/eclipse/rdf4j/query/parser/sparql/TupleExprBuilderTest.java b/core/queryparser/sparql/src/test/java/org/eclipse/rdf4j/query/parser/sparql/TupleExprBuilderTest.java
index 37c1bf3e540..90ec4eecaee 100644
--- a/core/queryparser/sparql/src/test/java/org/eclipse/rdf4j/query/parser/sparql/TupleExprBuilderTest.java
+++ b/core/queryparser/sparql/src/test/java/org/eclipse/rdf4j/query/parser/sparql/TupleExprBuilderTest.java
@@ -19,7 +19,9 @@
 import java.util.List;
 
 import org.eclipse.rdf4j.model.impl.SimpleValueFactory;
+import org.eclipse.rdf4j.query.algebra.BindingSetAssignment;
 import org.eclipse.rdf4j.query.algebra.Extension;
+import org.eclipse.rdf4j.query.algebra.Join;
 import org.eclipse.rdf4j.query.algebra.Order;
 import org.eclipse.rdf4j.query.algebra.Projection;
 import org.eclipse.rdf4j.query.algebra.Service;
@@ -82,6 +84,29 @@ public void testAskQuerySolutionModifiers() {
 
 	}
 
+	@Test
+	public void testValuesOptionalQuery() throws Exception {
+		String query = "select ?parent ?child\n"
+				+ "where {\n"
+				+ "    values ?type {<owl:Class>}\n"
+				+ "    ?parent <rdf:type> ?type .\n"
+				+ "    optional {\n"
+				+ "        ?child <rdfs:subClassOf> ?parent ;\n"
+				+ "               <rdf:type> ?type .\n"
+				+ "    }\n"
+				+ "}";
+
+		TupleExprBuilder builder = new TupleExprBuilder(SimpleValueFactory.getInstance());
+		ASTQueryContainer qc = SyntaxTreeBuilder.parseQuery(query);
+		TupleExpr result = builder.visit(qc, null);
+
+		assertThat(result).isInstanceOf(Projection.class);
+		Join topJoin = (Join) ((Projection) result).getArg();
+
+		assertThat(topJoin.getLeftArg()).isInstanceOf(BindingSetAssignment.class);
+
+	}
+
 	@Test
 	public void testNegatedPathWithFixedObject() {
 		String query = "ASK WHERE { ?s !<http://example.org/p> <http://example.org/o> . }";
diff --git a/core/sail/nativerdf/src/test/java/org/eclipse/rdf4j/sail/nativerdf/benchmark/SPARQLValuesClauseBenchmark.java b/core/sail/nativerdf/src/test/java/org/eclipse/rdf4j/sail/nativerdf/benchmark/SPARQLValuesClauseBenchmark.java
index 4917ef0341c..d3560e6ca92 100644
--- a/core/sail/nativerdf/src/test/java/org/eclipse/rdf4j/sail/nativerdf/benchmark/SPARQLValuesClauseBenchmark.java
+++ b/core/sail/nativerdf/src/test/java/org/eclipse/rdf4j/sail/nativerdf/benchmark/SPARQLValuesClauseBenchmark.java
@@ -153,6 +153,19 @@ public void afterClass() {
 	@Benchmark
 	public long valuesOptionalQuery() {
 		try (SailRepositoryConnection connection = repository.getConnection()) {
+//
+//			System.out.println("ONLY PARSED:");
+//			System.out.println(connection.prepareTupleQuery(query_with_values_clause));
+//			System.out.println("\nUNOPTIMIZED:");
+//			System.out.println(
+//					connection.prepareTupleQuery(query_with_values_clause).explain(Explanation.Level.Unoptimized));
+//
+//			System.out.println();
+//			System.out.println("OPTIMIZED:");
+//			System.out.println(
+//					connection.prepareTupleQuery(query_with_values_clause).explain(Explanation.Level.Optimized));
+
+//			return 0L;
 			return connection
 					.prepareTupleQuery(query_with_values_clause)
 					.evaluate()
@@ -164,6 +177,7 @@ public long valuesOptionalQuery() {
 	@Benchmark
 	public long simpleEquivalentQuery() {
 		try (SailRepositoryConnection connection = repository.getConnection()) {
+
 			return connection
 					.prepareTupleQuery(query_without_values_clause)
 					.evaluate()