diff --git a/org.hl7.fhir.dstu3/src/test/java/org/hl7/fhir/dstu3/utils/FhirPathTests.java b/org.hl7.fhir.dstu3/src/test/java/org/hl7/fhir/dstu3/utils/FhirPathTests.java
index 800668cc6..f595e238a 100644
--- a/org.hl7.fhir.dstu3/src/test/java/org/hl7/fhir/dstu3/utils/FhirPathTests.java
+++ b/org.hl7.fhir.dstu3/src/test/java/org/hl7/fhir/dstu3/utils/FhirPathTests.java
@@ -1,15 +1,22 @@
 package org.hl7.fhir.dstu3.utils;
 
-
 import org.hl7.fhir.dstu3.context.IWorkerContext;
 import org.hl7.fhir.dstu3.model.Base;
 import org.hl7.fhir.dstu3.model.ExpressionNode;
+import org.hl7.fhir.dstu3.model.StringType;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.Mockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+
 @ExtendWith(MockitoExtension.class)
 public class FhirPathTests {
 
@@ -43,7 +50,12 @@ public class FhirPathTests {
 
     expressionNode.getParameters().add(expressionNodeB);
     expressionNode.getParameters().add(expressionNodeC);
-    engine.evaluate(appContext, resource, base, expressionNode);
+    List<Base> result = engine.evaluate(appContext, resource, base, expressionNode);
 
+    assertEquals(1, result.size());
+    Base onlyResult = result.get(0);
+    assertTrue(onlyResult instanceof StringType);
+    assertEquals("base", ((StringType)result.get(0)).asStringValue());
+    Mockito.verify(engine, times(2)).convertToString(any());
   }
 }
\ No newline at end of file