diff --git a/doc/examples/constraint-validation/constraint-validation.md b/doc/examples/constraint-validation/constraint-validation.md
index a5506de5..3df9ef36 100644
--- a/doc/examples/constraint-validation/constraint-validation.md
+++ b/doc/examples/constraint-validation/constraint-validation.md
@@ -221,10 +221,10 @@ Validation of constraint failed for the constraint: More than one person matches
           .
       }
 Evidences:
-| person                                                                                    | firstName | lastName |
-+-------------------------------------------------------------------------------------------+-----------+----------+
-| http://onto.fel.cvut.cz/ontologies/s-pipes/examples/constraint-validation/people/person-2 | Peter     | Hnizdo   |
-| http://onto.fel.cvut.cz/ontologies/s-pipes/examples/constraint-validation/people/person-1 | Pavel     | Hnizdo   |
+| person                                                                                      | firstName | lastName |
++---------------------------------------------------------------------------------------------+-----------+----------+
+| <http://onto.fel.cvut.cz/ontologies/s-pipes/examples/constraint-validation/people/person-2> | "Peter"   | "Hnizdo" |
+| <http://onto.fel.cvut.cz/ontologies/s-pipes/examples/constraint-validation/people/person-1> | "Pavel"   | "Hnizdo" |
 ```
 
 If `execution.exitOnError` is set to `true` in `config-core.properties` , the pipeline will not proceed with execution, and an error validation response in JSON-LD will be retrieved:
diff --git a/s-pipes-core/src/main/java/cz/cvut/spipes/exception/ValidationConstraintFailedException.java b/s-pipes-core/src/main/java/cz/cvut/spipes/exception/ValidationConstraintFailedException.java
index 1f4b1dcd..f5f02947 100644
--- a/s-pipes-core/src/main/java/cz/cvut/spipes/exception/ValidationConstraintFailedException.java
+++ b/s-pipes-core/src/main/java/cz/cvut/spipes/exception/ValidationConstraintFailedException.java
@@ -1,6 +1,7 @@
 package cz.cvut.spipes.exception;
 
 import cz.cvut.spipes.modules.Module;
+import cz.cvut.spipes.util.RDFNodeUtils;
 import org.apache.jena.rdf.model.RDFNode;
 import org.apache.jena.rdf.model.Resource;
 import org.jetbrains.annotations.NonNls;
@@ -80,7 +81,7 @@ private Map<String, Integer> determineColumnWidths() {
         for (Map<String, RDFNode> row : evidences) {
             for (Map.Entry<String, RDFNode> entry : row.entrySet()) {
                 int currentWidth = columnWidths.get(entry.getKey());
-                int dataWidth = entry.getValue().toString().length();
+                int dataWidth = RDFNodeUtils.toString(entry.getValue()).length();
                 columnWidths.put(entry.getKey(), Math.max(currentWidth, dataWidth));
             }
         }
@@ -107,7 +108,7 @@ private void buildRows(StringBuilder tableBuilder, String format) {
         for (Map<String, RDFNode> row : evidences) {
             List<String> values = new ArrayList<>();
             for (String key : row.keySet()) {
-                values.add(row.get(key).toString());
+                values.add(RDFNodeUtils.toString(row.get(key)));
             }
             tableBuilder.append(String.format(format, values.toArray()));
         }