diff --git a/workflow/src/main/java/com/google/android/fhir/workflow/FhirEngineLibraryContentProvider.kt b/workflow/src/main/java/com/google/android/fhir/workflow/FhirEngineLibraryContentProvider.kt
index b8eb653d7b..af17488b2b 100644
--- a/workflow/src/main/java/com/google/android/fhir/workflow/FhirEngineLibraryContentProvider.kt
+++ b/workflow/src/main/java/com/google/android/fhir/workflow/FhirEngineLibraryContentProvider.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Google LLC
+ * Copyright 2022 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,7 +26,7 @@ class FhirEngineLibraryContentProvider(adapterFactory: AdapterFactory) :
   BaseFhirLibraryContentProvider(adapterFactory) {
   val libs = mutableMapOf<String, Library>()
 
-  override fun getLibrary(libraryIdentifier: VersionedIdentifier): IBaseResource {
-    return libs[libraryIdentifier.id]!!
+  override fun getLibrary(libraryIdentifier: VersionedIdentifier): IBaseResource? {
+    return libs[libraryIdentifier.id]
   }
 }