diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/BaseWorkerContext.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/BaseWorkerContext.java
index 73feac21f..ab1306bbd 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/BaseWorkerContext.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/BaseWorkerContext.java
@@ -724,10 +724,13 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
   }
 
   //TESTME
-  public ValueSetExpansionOutcome expandVS(ValueSet vs, boolean cacheOk, boolean heirarchical, boolean incompleteOk, Parameters p)  {
-    if (p == null) {
+  public ValueSetExpansionOutcome expandVS(ValueSet vs, boolean cacheOk, boolean hierarchical, boolean incompleteOk, Parameters pIn)  {
+    if (pIn == null) {
       throw new Error(formatMessage(I18nConstants.NO_PARAMETERS_PROVIDED_TO_EXPANDVS));
     }
+
+    Parameters p = pIn.copy();
+
     if (vs.hasExpansion()) {
       return new ValueSetExpansionOutcome(vs.copy());
     }
@@ -741,7 +744,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       codeSystemsUsed.add(inc.getSystem());
     }
 
-    CacheToken cacheToken = txCache.generateExpandToken(vs, heirarchical);
+    CacheToken cacheToken = txCache.generateExpandToken(vs, hierarchical);
     ValueSetExpansionOutcome res;
     if (cacheOk) {
       res = txCache.getExpansion(cacheToken);
@@ -750,7 +753,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
       }
     }
     p.setParameter("includeDefinition", false);
-    p.setParameter("excludeNested", !heirarchical);
+    p.setParameter("excludeNested", !hierarchical);
     if (incompleteOk) {
       p.setParameter("incomplete-ok", true);      
     }
@@ -758,7 +761,7 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     List<String> allErrors = new ArrayList<>();
     
     // ok, first we try to expand locally
-    ValueSetExpanderSimple vse = new ValueSetExpanderSimple(this);
+    ValueSetExpanderSimple vse = constructValueSetExpanderSimple();
     try {
       res = vse.expand(vs, p);
       allErrors.addAll(vse.getAllErrors());
@@ -1000,6 +1003,10 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
     return res;
   }
 
+  protected ValueSetExpanderSimple constructValueSetExpanderSimple() {
+    return new ValueSetExpanderSimple(this);
+  }
+
   protected ValueSetCheckerSimple constructValueSetCheckerSimple( ValidationOptions options,  ValueSet vs,  ValidationContextCarrier ctxt) {
     return new ValueSetCheckerSimple(options, vs, this, ctxt);
   }
diff --git a/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/context/SimpleWorkerContextTests.java b/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/context/SimpleWorkerContextTests.java
index 72130aa55..188b32440 100644
--- a/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/context/SimpleWorkerContextTests.java
+++ b/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/context/SimpleWorkerContextTests.java
@@ -4,8 +4,10 @@ import org.hl7.fhir.r5.model.*;
 import org.hl7.fhir.r5.terminologies.TerminologyClient;
 import org.hl7.fhir.r5.terminologies.ValueSetCheckerSimple;
 import org.hl7.fhir.r5.terminologies.ValueSetExpander;
+import org.hl7.fhir.r5.terminologies.ValueSetExpanderSimple;
 import org.hl7.fhir.r5.utils.validation.ValidationContextCarrier;
 import org.hl7.fhir.utilities.ToolingClientLogger;
+import org.hl7.fhir.utilities.graphql.Value;
 import org.hl7.fhir.utilities.validation.ValidationOptions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -26,6 +28,7 @@ import static org.mockito.Mockito.times;
 @ExtendWith(MockitoExtension.class)
 public class SimpleWorkerContextTests {
 
+  private static final String DUMMY_URL = "dummyUrl";
   @Spy
   SimpleWorkerContext context;
 
@@ -45,11 +48,14 @@ public class SimpleWorkerContextTests {
   IWorkerContext.ValidationResult expectedValidationResult;
 
   @Mock
-  ValueSetExpander.ValueSetExpansionOutcome expectedExansionResult;
+  ValueSetExpander.ValueSetExpansionOutcome expectedExpansionResult;
 
   @Mock
   ValueSetCheckerSimple valueSetCheckerSimple;
 
+  @Mock
+  ValueSetExpanderSimple valueSetExpanderSimple;
+
   @Mock
   Parameters pIn;
 
@@ -79,6 +85,19 @@ public class SimpleWorkerContextTests {
     }
   }
 
+  public class ParametersMatcher implements ArgumentMatcher<Parameters> {
+    private Parameters left;
+
+    ParametersMatcher(Parameters left) {
+      this.left = left;
+    }
+
+    @Override
+    public boolean matches(Parameters right) {
+      return true;
+    }
+  }
+
   @Test
   public void testValidateCodingWithCache() throws IOException {
     ValidationOptions validationOptions = new ValidationOptions().guessSystem().setVersionFlexible(false);
@@ -211,11 +230,11 @@ public class SimpleWorkerContextTests {
     vs.getCompose().getInclude().add(inc);
 
     Mockito.doReturn(cacheToken).when(terminologyCache).generateExpandToken(argThat(new ValueSetMatcher(vs)),eq(true));
-    Mockito.doReturn(expectedExansionResult).when(terminologyCache).getExpansion(cacheToken);
+    Mockito.doReturn(expectedExpansionResult).when(terminologyCache).getExpansion(cacheToken);
 
     ValueSetExpander.ValueSetExpansionOutcome actualExpansionResult = context.expandVS(inc, true);
 
-    assertEquals(expectedExansionResult, actualExpansionResult);
+    assertEquals(expectedExpansionResult, actualExpansionResult);
 
     Mockito.verify(terminologyCache).getExpansion(cacheToken);
     Mockito.verify(terminologyCache, times(0)).cacheExpansion(any(), any(), anyBoolean());
@@ -247,4 +266,53 @@ public class SimpleWorkerContextTests {
     Mockito.verify(terminologyCache).getExpansion(cacheToken);
     Mockito.verify(terminologyCache).cacheExpansion(cacheToken, actualExpansionResult,true);
   }
+
+  @Test
+  public void testExpandValueSet4ArgsWithCache() throws IOException {
+
+    ValueSet.ConceptSetComponent inc = new ValueSet.ConceptSetComponent();
+
+    ValueSet vs = new ValueSet();
+    vs.setUrl(DUMMY_URL);
+
+    Mockito.doReturn(cacheToken).when(terminologyCache).generateExpandToken(vs,true);
+    Mockito.doReturn(expectedExpansionResult).when(terminologyCache).getExpansion(cacheToken);
+
+    Parameters pIn = new Parameters();
+
+    ValueSetExpander.ValueSetExpansionOutcome actualExpansionResult = context.expandVS(vs, true,  true, true, pIn);
+
+    assertEquals(expectedExpansionResult, actualExpansionResult);
+
+    Mockito.verify(terminologyCache).getExpansion(cacheToken);
+    Mockito.verify(terminologyCache, times(0)).cacheExpansion(any(), any(), anyBoolean());
+    Mockito.verify(terminologyClient, times(0)).expandValueset(any(), any(), any());
+  }
+
+  @Test
+  public void testExpandValueSet4ArgsWithValueSetExpanderSimple() throws IOException {
+
+    ValueSet.ConceptSetComponent inc = new ValueSet.ConceptSetComponent();
+
+    ValueSet vs = new ValueSet();
+    vs.setUrl(DUMMY_URL);
+
+    Mockito.doReturn(cacheToken).when(terminologyCache).generateExpandToken(vs,true);
+
+    Parameters pIn = new Parameters();
+
+    Mockito.doReturn(vs).when(expectedExpansionResult).getValueset();
+
+    Mockito.doReturn(expectedExpansionResult).when(valueSetExpanderSimple).expand(eq(vs), argThat(new ParametersMatcher(pIn)));
+
+    Mockito.doReturn(valueSetExpanderSimple).when(context).constructValueSetExpanderSimple();
+
+    ValueSetExpander.ValueSetExpansionOutcome actualExpansionResult = context.expandVS(vs, true,  true, true, pIn);
+
+    assertEquals(expectedExpansionResult, actualExpansionResult);
+
+    Mockito.verify(terminologyCache).getExpansion(cacheToken);
+    Mockito.verify(terminologyCache, times(0)).cacheExpansion(any(), any(), anyBoolean());
+    Mockito.verify(terminologyClient, times(0)).expandValueset(any(), any(), any());
+  }
 }