diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonRenderer.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonRenderer.java
index 2e69deade..59344bac9 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonRenderer.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonRenderer.java
@@ -115,14 +115,14 @@ public class ComparisonRenderer implements IEvaluationContext {
   }
 
   private void dumpBinaries() throws IOException {
-    if (contextLeft != null && contextLeft.getBinaries() != null) {
-      for (String k : contextLeft.getBinaries().keySet()) {
-        TextFile.bytesToFile(contextLeft.getBinaries().get(k), Utilities.path(folder, k));
+    if (contextLeft != null && contextLeft.getBinaryKeysAsSet() != null) {
+      for (String k : contextLeft.getBinaryKeysAsSet()) {
+        TextFile.bytesToFile(contextLeft.getBinaryForKey(k), Utilities.path(folder, k));
       }
     }
-    if (contextRight != null && contextRight.getBinaries() != null) {
-      for (String k : contextRight.getBinaries().keySet()) {
-        TextFile.bytesToFile(contextRight.getBinaries().get(k), Utilities.path(folder, k));
+    if (contextRight != null && contextRight.getBinaryKeysAsSet() != null) {
+      for (String k : contextRight.getBinaryKeysAsSet()) {
+        TextFile.bytesToFile(contextRight.getBinaryForKey(k), Utilities.path(folder, k));
       }
     }
   }
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 0849cd7e2..ec56f847f 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
@@ -2161,10 +2161,18 @@ public abstract class BaseWorkerContext extends I18nBase implements IWorkerConte
   }
 
   @Override
-  public Map<String, byte[]> getBinaries() {
-    return binaries;
+  public Set<String> getBinaryKeysAsSet() { return binaries.keySet(); }
+
+  @Override
+  public boolean hasBinaryKey(String binaryKey) {
+    return binaries.containsKey(binaryKey);
   }
-  
+
+  @Override
+  public byte[] getBinaryForKey(String binaryKey) {
+    return binaries.get(binaryKey);
+  }
+
   public void finishLoading() {
     for (StructureDefinition sd : listStructures()) {
       try {
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/IWorkerContext.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/IWorkerContext.java
index 020ddc8b9..3521f353d 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/IWorkerContext.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/IWorkerContext.java
@@ -833,7 +833,28 @@ public interface IWorkerContext {
   public void setUcumService(UcumService ucumService);
 
   public String getLinkForUrl(String corePath, String s);
-  public Map<String, byte[]> getBinaries();
+
+  /**
+   * Returns a set of keys that can be used to get binaries from this context.
+   *
+   * @return a set of binaries or null
+   */
+  public Set<String> getBinaryKeysAsSet();
+
+  /**
+   * Returns true if this worker context contains a binary for this key.
+   *
+   * @param binaryKey
+   * @return true if binary is available for this key
+   */
+  public boolean hasBinaryKey(String binaryKey);
+
+  /**
+   * Returns the binary for the key
+   * @param binaryKey
+   * @return
+   */
+  public byte[] getBinaryForKey(String binaryKey);
 
   /**
    * Load relevant resources of the appropriate types (as specified by the loader) from the nominated package
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/XVerExtensionManager.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/XVerExtensionManager.java
index 7e577452b..071676dc8 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/XVerExtensionManager.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/XVerExtensionManager.java
@@ -52,9 +52,9 @@ public class XVerExtensionManager {
     String v = url.substring(20, 23);
     String e = url.substring(54);
     if (!lists.containsKey(v)) {
-      if (context.getBinaries().containsKey("xver-paths-"+v+".json")) {
+      if (context.hasBinaryKey("xver-paths-"+v+".json")) {
         try {
-          lists.put(v, JsonTrackingParser.parseJson(context.getBinaries().get("xver-paths-"+v+".json")));
+          lists.put(v, JsonTrackingParser.parseJson(context.getBinaryForKey("xver-paths-"+v+".json")));
         } catch (IOException e1) {
           throw new FHIRException(e);
         }
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ComparisonService.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ComparisonService.java
index 795739d76..be5907233 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ComparisonService.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ComparisonService.java
@@ -67,11 +67,11 @@ public class ComparisonService {
     System.out.println("Generating output to " + dest + "...");
     Utilities.createDirectory(dest);
     ComparisonRenderer cr = new ComparisonRenderer(validator.getContext(), validator.getContext(), dest, session);
-    cr.getTemplates().put("CodeSystem", new String(validator.getContext().getBinaries().get("template-comparison-CodeSystem.html")));
-    cr.getTemplates().put("ValueSet", new String(validator.getContext().getBinaries().get("template-comparison-ValueSet.html")));
-    cr.getTemplates().put("Profile", new String(validator.getContext().getBinaries().get("template-comparison-Profile.html")));
-    cr.getTemplates().put("Index", new String(validator.getContext().getBinaries().get("template-comparison-index.html")));
-    cr.getTemplates().put("CapabilityStatement", new String(validator.getContext().getBinaries().get("template-comparison-CapabilityStatement.html")));
+    cr.getTemplates().put("CodeSystem", new String(validator.getContext().getBinaryForKey("template-comparison-CodeSystem.html")));
+    cr.getTemplates().put("ValueSet", new String(validator.getContext().getBinaryForKey("template-comparison-ValueSet.html")));
+    cr.getTemplates().put("Profile", new String(validator.getContext().getBinaryForKey("template-comparison-Profile.html")));
+    cr.getTemplates().put("Index", new String(validator.getContext().getBinaryForKey("template-comparison-index.html")));
+    cr.getTemplates().put("CapabilityStatement", new String(validator.getContext().getBinaryForKey("template-comparison-CapabilityStatement.html")));
     File htmlFile = cr.render(left, right);
     Desktop.getDesktop().browse(htmlFile.toURI());
     System.out.println("Done");