diff --git a/bazel/repository_locations.bzl b/bazel/repository_locations.bzl
index 268d7e2bebb6..c89bbb25e854 100644
--- a/bazel/repository_locations.bzl
+++ b/bazel/repository_locations.bzl
@@ -296,10 +296,10 @@ REPOSITORY_LOCATIONS = dict(
         urls = ["https://storage.googleapis.com/quiche-envoy-integration/googleurl_dbf5ad147f60afc125e99db7549402af49a5eae8.tar.gz"],
     ),
     com_google_cel_cpp = dict(
-        sha256 = "7eddffdb231e7c82f60c597cd38e742fbc0c48f54ca33015ac0a3d22bd51bba3",
-        strip_prefix = "cel-cpp-d88a4822af1864b481b31b12c2ecc4e631a7f8a9",
-        # 2019-04-13
-        urls = ["https://github.com/google/cel-cpp/archive/d88a4822af1864b481b31b12c2ecc4e631a7f8a9.tar.gz"],
+        sha256 = "d773ee368053f404eada87b59c9e545b2e21118ebb0577ac3e942a06518f6fd2",
+        strip_prefix = "cel-cpp-0.2.0",
+        # 2020-05-11
+        urls = ["https://github.com/google/cel-cpp/archive/v0.2.0.tar.gz"],
     ),
     com_github_google_flatbuffers = dict(
         sha256 = "b8efbc25721e76780752bad775a97c3f77a0250271e2db37fc747b20e8b0f24a",
diff --git a/source/extensions/common/wasm/context.h b/source/extensions/common/wasm/context.h
index 84f57038c347..b65f98beee41 100644
--- a/source/extensions/common/wasm/context.h
+++ b/source/extensions/common/wasm/context.h
@@ -322,7 +322,7 @@ class Context : public Logger::Loggable<Logger::Id::wasm>,
     static const std::vector<google::api::expr::runtime::CelAttributePattern> empty;
     return empty;
   }
-  const Protobuf::FieldMask unknown_paths() const override {
+  const Protobuf::FieldMask& unknown_paths() const override {
     return Protobuf::FieldMask::default_instance();
   }
 
diff --git a/source/extensions/common/wasm/foreign.cc b/source/extensions/common/wasm/foreign.cc
index bec09cbfa973..4f27fe6fa40a 100644
--- a/source/extensions/common/wasm/foreign.cc
+++ b/source/extensions/common/wasm/foreign.cc
@@ -170,8 +170,13 @@ class EvaluateExpressionFactory : public ExpressionFactory, public ForeignFuncti
         ENVOY_LOG(debug, "expr_evaluate error: {}", eval_status.status().message());
         return WasmResult::InternalFailure;
       }
+      auto value = eval_status.value();
+      if (value.IsError()) {
+        ENVOY_LOG(debug, "expr_evaluate value error: {}", value.ErrorOrDie()->message());
+        return WasmResult::InternalFailure;
+      }
       std::string result;
-      auto serialize_status = serializeValue(eval_status.value(), &result);
+      auto serialize_status = serializeValue(value, &result);
       if (serialize_status != WasmResult::Ok) {
         return serialize_status;
       }