diff --git a/google-cloud-storage/src/test/java/com/google/cloud/storage/it/ITGrpcInterceptorTest.java b/google-cloud-storage/src/test/java/com/google/cloud/storage/it/ITGrpcInterceptorTest.java
index 0e52171b8d..f7c9d1f153 100644
--- a/google-cloud-storage/src/test/java/com/google/cloud/storage/it/ITGrpcInterceptorTest.java
+++ b/google-cloud-storage/src/test/java/com/google/cloud/storage/it/ITGrpcInterceptorTest.java
@@ -86,7 +86,8 @@ public void grpcStorageOptions_allowSpecifyingInterceptor() throws Exception {
     System.out.println("requestParams = " + requestParams);
 
     String expected = String.format("project=projects/%s", options.getProjectId());
-    assertThat(requestParams).contains(expected);
+    String expectedEncoded = String.format("project=projects%%2F%s", options.getProjectId());
+    assertThat(requestParams).containsAnyOf(expected, expectedEncoded);
   }
 
   private static final class Interceptor implements ClientInterceptor {