diff --git a/sandboxed_api/BUILD b/sandboxed_api/BUILD
index d920b2ee..f08986cc 100644
--- a/sandboxed_api/BUILD
+++ b/sandboxed_api/BUILD
@@ -13,7 +13,6 @@
 # limitations under the License.
 
 load("//sandboxed_api/bazel:build_defs.bzl", "sapi_platform_copts")
-load("//sandboxed_api/bazel:proto.bzl", "sapi_proto_library")
 
 package(default_visibility = ["//sandboxed_api:__subpackages__"])
 
@@ -31,12 +30,6 @@ cc_library(
     ],
 )
 
-sapi_proto_library(
-    name = "proto_arg",
-    srcs = ["proto_arg.proto"],
-    visibility = ["//visibility:public"],
-)
-
 cc_library(
     name = "embed_file",
     srcs = [
@@ -140,14 +133,12 @@ cc_library(
 cc_library(
     name = "vars",
     srcs = [
-        "proto_helper.cc",
         "rpcchannel.cc",
         "var_abstract.cc",
         "var_int.cc",
         "var_lenval.cc",
     ],
     hdrs = [
-        "proto_helper.h",
         "rpcchannel.h",
         "var_abstract.h",
         "var_array.h",
@@ -165,10 +156,10 @@ cc_library(
     deps = [
         ":call",
         ":lenval_core",
-        ":proto_arg_cc_proto",
         ":var_type",
         "//sandboxed_api/sandbox2:comms",
         "//sandboxed_api/sandbox2:util",
+        "//sandboxed_api/util:proto_helper",
         "//sandboxed_api/util:status",
         "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/log",
@@ -192,12 +183,12 @@ cc_library(
     deps = [
         ":call",
         ":lenval_core",
-        ":proto_arg_cc_proto",
         ":var_type",
-        ":vars",
         "//sandboxed_api/sandbox2:comms",
         "//sandboxed_api/sandbox2:forkingclient",
         "//sandboxed_api/sandbox2:logsink",
+        "//sandboxed_api/util:proto_arg_cc_proto",
+        "//sandboxed_api/util:proto_helper",
         "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/base:dynamic_annotations",
         "@com_google_absl//absl/flags:parse",
diff --git a/sandboxed_api/CMakeLists.txt b/sandboxed_api/CMakeLists.txt
index 0ab952ec..48c820e1 100644
--- a/sandboxed_api/CMakeLists.txt
+++ b/sandboxed_api/CMakeLists.txt
@@ -31,20 +31,6 @@ target_link_libraries(sapi_config
   PUBLIC absl::config
 )
 
-# sandboxed_api:proto_arg
-sapi_protobuf_generate_cpp(_sapi_proto_arg_pb_cc _sapi_proto_arg_pb_h
-  proto_arg.proto
-)
-add_library(sapi_proto_arg_proto ${SAPI_LIB_TYPE}
-  ${_sapi_proto_arg_pb_cc}
-  ${_sapi_proto_arg_pb_h}
-)
-add_library(sapi::proto_arg_proto ALIAS sapi_proto_arg_proto)
-target_link_libraries(sapi_proto_arg_proto PRIVATE
-  protobuf::libprotobuf
-  sapi::base
-)
-
 # sandboxed_api:embed_file
 add_library(sapi_embed_file ${SAPI_LIB_TYPE}
   embed_file.cc
@@ -129,8 +115,6 @@ target_link_libraries(sapi_var_type PRIVATE
 
 # sandboxed_api:vars
 add_library(sapi_vars ${SAPI_LIB_TYPE}
-  proto_helper.cc
-  proto_helper.h
   rpcchannel.cc
   rpcchannel.h
   var_abstract.cc
@@ -162,10 +146,10 @@ target_link_libraries(sapi_vars
           sapi::base
           sapi::call
           sapi::lenval_core
-          sapi::proto_arg_proto
           sapi::status
           sapi::var_type
   PUBLIC absl::log
+         sapi::proto_helper
 )
 
 # sandboxed_api:client
@@ -191,7 +175,7 @@ target_link_libraries(sapi_client
           sapi::call
           sapi::lenval_core
           sapi::proto_arg_proto
-          sapi::vars
+          sapi::proto_helper
           ${CMAKE_DL_LIBS}
 )
 
diff --git a/sandboxed_api/client.cc b/sandboxed_api/client.cc
index 1c8d56f5..4459d92e 100644
--- a/sandboxed_api/client.cc
+++ b/sandboxed_api/client.cc
@@ -39,11 +39,11 @@
 #include "google/protobuf/message.h"
 #include "sandboxed_api/call.h"
 #include "sandboxed_api/lenval_core.h"
-#include "sandboxed_api/proto_arg.pb.h"
-#include "sandboxed_api/proto_helper.h"
 #include "sandboxed_api/sandbox2/comms.h"
 #include "sandboxed_api/sandbox2/forkingclient.h"
 #include "sandboxed_api/sandbox2/logsink.h"
+#include "sandboxed_api/util/proto_arg.pb.h"
+#include "sandboxed_api/util/proto_helper.h"
 #include "sandboxed_api/var_type.h"
 
 #include <ffi.h>
diff --git a/sandboxed_api/util/BUILD b/sandboxed_api/util/BUILD
index 9dac4199..670e6f36 100644
--- a/sandboxed_api/util/BUILD
+++ b/sandboxed_api/util/BUILD
@@ -96,6 +96,25 @@ cc_test(
     ],
 )
 
+sapi_proto_library(
+    name = "proto_arg",
+    srcs = ["proto_arg.proto"],
+    visibility = ["//visibility:public"],
+)
+
+cc_library(
+    name = "proto_helper",
+    srcs = ["proto_helper.cc"],
+    hdrs = ["proto_helper.h"],
+    copts = sapi_platform_copts(),
+    deps = [
+        ":proto_arg_cc_proto",
+        ":status",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:statusor",
+    ],
+)
+
 # Small support library emulating verbose logging using Abseil's raw logging
 # facility.
 cc_library(
diff --git a/sandboxed_api/util/CMakeLists.txt b/sandboxed_api/util/CMakeLists.txt
index ae91c16f..36c299eb 100644
--- a/sandboxed_api/util/CMakeLists.txt
+++ b/sandboxed_api/util/CMakeLists.txt
@@ -47,6 +47,36 @@ target_link_libraries(sapi_util_fileops PRIVATE
   sapi::base
 )
 
+# sandboxed_api/util:proto_arg
+sapi_protobuf_generate_cpp(_sapi_proto_arg_pb_cc _sapi_proto_arg_pb_h
+  proto_arg.proto
+)
+add_library(sapi_util_proto_arg_proto ${SAPI_LIB_TYPE}
+  ${_sapi_proto_arg_pb_cc}
+  ${_sapi_proto_arg_pb_h}
+)
+add_library(sapi::proto_arg_proto ALIAS sapi_util_proto_arg_proto)
+target_link_libraries(sapi_util_proto_arg_proto PRIVATE
+  protobuf::libprotobuf
+  sapi::base
+)
+
+# sandboxed_api/util:proto_helper
+add_library(sapi_util_proto_helper ${SAPI_LIB_TYPE}
+  proto_helper.cc
+  proto_helper.h
+)
+add_library(sapi::proto_helper ALIAS sapi_util_proto_helper)
+target_link_libraries(sapi_util_proto_helper
+  PRIVATE sapi::base
+  PUBLIC absl::core_headers
+         absl::status
+         absl::statusor
+         sapi::proto_arg_proto
+         sapi::status
+)
+
+
 # sandboxed_api/util:raw_logging
 add_library(sapi_util_raw_logging ${SAPI_LIB_TYPE}
   raw_logging.cc
diff --git a/sandboxed_api/proto_arg.proto b/sandboxed_api/util/proto_arg.proto
similarity index 100%
rename from sandboxed_api/proto_arg.proto
rename to sandboxed_api/util/proto_arg.proto
diff --git a/sandboxed_api/proto_helper.cc b/sandboxed_api/util/proto_helper.cc
similarity index 97%
rename from sandboxed_api/proto_helper.cc
rename to sandboxed_api/util/proto_helper.cc
index 0c3623b8..bea416a3 100644
--- a/sandboxed_api/proto_helper.cc
+++ b/sandboxed_api/util/proto_helper.cc
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "sandboxed_api/proto_helper.h"
+#include "sandboxed_api/util/proto_helper.h"
 
 #include <cstddef>
 #include <cstdint>
diff --git a/sandboxed_api/proto_helper.h b/sandboxed_api/util/proto_helper.h
similarity index 89%
rename from sandboxed_api/proto_helper.h
rename to sandboxed_api/util/proto_helper.h
index 267bbba2..547c0b34 100644
--- a/sandboxed_api/proto_helper.h
+++ b/sandboxed_api/util/proto_helper.h
@@ -14,8 +14,8 @@
 
 // Utility functions for protobuf handling.
 
-#ifndef SANDBOXED_API_PROTO_HELPER_H_
-#define SANDBOXED_API_PROTO_HELPER_H_
+#ifndef SANDBOXED_API_UTIL_PROTO_HELPER_H_
+#define SANDBOXED_API_UTIL_PROTO_HELPER_H_
 
 #include <cstddef>
 #include <cstdint>
@@ -24,7 +24,7 @@
 
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
-#include "sandboxed_api/proto_arg.pb.h"
+#include "sandboxed_api/util/proto_arg.pb.h"
 #include "sandboxed_api/util/status_macros.h"
 
 namespace sapi {
@@ -51,4 +51,4 @@ absl::StatusOr<T> DeserializeProto(const char* data, size_t len) {
 
 }  // namespace sapi
 
-#endif  // SANDBOXED_API_PROTO_HELPER_H_
+#endif  // SANDBOXED_API_UTIL_PROTO_HELPER_H_
diff --git a/sandboxed_api/var_proto.h b/sandboxed_api/var_proto.h
index 0f86ca3d..79b3117f 100644
--- a/sandboxed_api/var_proto.h
+++ b/sandboxed_api/var_proto.h
@@ -32,7 +32,7 @@
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
 #include "absl/utility/utility.h"
-#include "sandboxed_api/proto_helper.h"
+#include "sandboxed_api/util/proto_helper.h"
 #include "sandboxed_api/util/status_macros.h"
 #include "sandboxed_api/var_lenval.h"
 #include "sandboxed_api/var_ptr.h"