diff --git a/src/main/java/se/liu/ida/hefquin/engine/data/impl/VocabularyMappingImpl.java b/src/main/java/se/liu/ida/hefquin/engine/data/impl/VocabularyMappingImpl.java
index 72cec7fe7..337dacf9a 100644
--- a/src/main/java/se/liu/ida/hefquin/engine/data/impl/VocabularyMappingImpl.java
+++ b/src/main/java/se/liu/ida/hefquin/engine/data/impl/VocabularyMappingImpl.java
@@ -339,7 +339,7 @@ public Graph getVocabularyMappingAsGraph() {
 	}
 
 	@Override
-	public Set<SolutionMapping> translateSolutionMapping( final SolutionMapping sm) {		
+	public Set<SolutionMapping> translateSolutionMapping( final SolutionMapping sm ) {
 		Set<BindingBuilder> bbs = new HashSet<>();
 		bbs.add( BindingBuilder.create() );
 		
@@ -384,7 +384,8 @@ public Set<SolutionMapping> translateSolutionMapping( final SolutionMapping sm)
 		
 		final Set<SolutionMapping> results = new HashSet<>();
 		for (final BindingBuilder b : bbs) {
-			results.add(new SolutionMappingImpl(b.build()));
+			final SolutionMapping translatedSM = new SolutionMappingImpl( b.build() );
+			results.add(translatedSM);
 		}
 		return results;
 	}
diff --git a/src/main/java/se/liu/ida/hefquin/engine/data/mappings/VocabularyMappingUtils.java b/src/main/java/se/liu/ida/hefquin/engine/data/mappings/VocabularyMappingUtils.java
index 9096692ca..37e6dce80 100644
--- a/src/main/java/se/liu/ida/hefquin/engine/data/mappings/VocabularyMappingUtils.java
+++ b/src/main/java/se/liu/ida/hefquin/engine/data/mappings/VocabularyMappingUtils.java
@@ -8,9 +8,11 @@
 import org.apache.jena.graph.Triple;
 import org.apache.jena.sparql.algebra.Op;
 import org.apache.jena.sparql.algebra.op.OpBGP;
+import org.apache.jena.sparql.algebra.op.OpFilter;
 import org.apache.jena.sparql.algebra.op.OpJoin;
 import org.apache.jena.sparql.algebra.op.OpSequence;
 import org.apache.jena.sparql.algebra.op.OpUnion;
+import org.apache.jena.sparql.expr.ExprList;
 
 import se.liu.ida.hefquin.engine.data.VocabularyMapping;
 import se.liu.ida.hefquin.engine.query.BGP;
@@ -21,6 +23,7 @@
 import se.liu.ida.hefquin.engine.query.impl.BGPImpl;
 import se.liu.ida.hefquin.engine.query.impl.GenericSPARQLGraphPatternImpl1;
 import se.liu.ida.hefquin.engine.query.impl.GenericSPARQLGraphPatternImpl2;
+import se.liu.ida.hefquin.engine.query.impl.QueryPatternUtils;
 import se.liu.ida.hefquin.engine.query.impl.SPARQLGroupPatternImpl;
 import se.liu.ida.hefquin.engine.query.impl.SPARQLUnionPatternImpl;
 import se.liu.ida.hefquin.engine.query.impl.TriplePatternImpl;
@@ -113,11 +116,9 @@ public static SPARQLGraphPattern translateGraphPattern( final Op op,
 		else if ( op instanceof OpUnion ) {
 			return translateGraphPattern( (OpUnion) op, vm );
 		}
-/* TODO
 		else if ( op instanceof OpFilter ) {
 			return translateGraphPattern( (OpFilter) op, vm );
 		}
-*/
 		else if ( op instanceof OpBGP ) {
 			return translateGraphPattern( (OpBGP) op, vm );
 		}
@@ -191,4 +192,19 @@ public static SPARQLGraphPattern translateGraphPattern( final OpSequence op,
 		return new SPARQLGroupPatternImpl(subPatterns);
 	}
 
+	public static SPARQLGraphPattern translateGraphPattern( final OpFilter op,
+	                                                        final VocabularyMapping vm ) {
+		final Op subOp = op.getSubOp();
+		final SPARQLGraphPattern translatedSubPlan = translateGraphPattern(subOp, vm);
+		final ExprList translatedExprs = translateExpressions( op.getExprs(), vm );
+		return QueryPatternUtils.merge(translatedExprs, translatedSubPlan);
+	}
+
+	public static ExprList translateExpressions( final ExprList exprs,
+	                                             final VocabularyMapping vm ) {
+		// TODO: translate the filter expressions
+
+		return exprs;
+	}
+
 }
diff --git a/src/main/java/se/liu/ida/hefquin/engine/queryproc/impl/loptimizer/ApplyVocabularyMappings.java b/src/main/java/se/liu/ida/hefquin/engine/queryproc/impl/loptimizer/ApplyVocabularyMappings.java
index 50a54bb7e..a832d0135 100644
--- a/src/main/java/se/liu/ida/hefquin/engine/queryproc/impl/loptimizer/ApplyVocabularyMappings.java
+++ b/src/main/java/se/liu/ida/hefquin/engine/queryproc/impl/loptimizer/ApplyVocabularyMappings.java
@@ -94,6 +94,7 @@ public LogicalPlan apply( final LogicalPlan inputPlan ) {
 		} else if (inputPlan.getRootOperator() instanceof LogicalOpFilter){
             final LogicalOpFilter filterOp = (LogicalOpFilter) inputPlan.getRootOperator();
             final LogicalPlan rw = rewriteToUseLocalVocabulary(inputPlan.getSubPlan(0));
+            // TODO: the expressions of 'filterOp' should be rewritten too
             return new LogicalPlanWithUnaryRootImpl(filterOp,rw);
         } else {
             throw new IllegalArgumentException("The given logical plan is not supported by this function because it has a root operator of type: " + inputPlan.getRootOperator().getClass().getName() );