diff --git a/mace/core/file_storage.cc b/mace/core/file_storage.cc
index 960cbf6120a3c1f523c15a62150693f538846b82..de9a67fa73a197d8bfe73ec27652fff2f0afd85f 100644
--- a/mace/core/file_storage.cc
+++ b/mace/core/file_storage.cc
@@ -49,25 +49,29 @@ std::unique_ptr<KVStorage> FileStorageFactory::CreateStorage(
 FileStorage::FileStorage(const std::string &file_path):
     file_path_(file_path) {}
 
-KVStorageStatus FileStorage::Load() {
+int FileStorage::Load() {
   struct stat st;
   if (stat(file_path_.c_str(), &st) == -1) {
     if (errno == ENOENT) {
-      return KVStorageStatus::STORAGE_FILE_NOT_EXIST;
+      LOG(INFO) << "File " << file_path_
+                << " does not exist";
+      return 0;
     } else {
-      LOG(WARNING) << "stat file " << file_path_
+      LOG(WARNING) << "Stat file " << file_path_
                    << " failed, error code: " << errno;
-      return KVStorageStatus::STORAGE_ERROR;
+      return -1;
     }
   }
   int fd = open(file_path_.c_str(), O_RDONLY);
   if (fd < 0) {
     if (errno == ENOENT) {
-      return KVStorageStatus::STORAGE_FILE_NOT_EXIST;
+      LOG(INFO) << "File " << file_path_
+                << " does not exist";
+      return 0;
     } else {
       LOG(WARNING) << "open file " << file_path_
                    << " failed, error code: " << errno;
-      return KVStorageStatus::STORAGE_ERROR;
+      return -1;
     }
   }
   size_t file_size = st.st_size;
@@ -84,7 +88,7 @@ KVStorageStatus FileStorage::Load() {
       LOG(WARNING) << "close file " << file_path_
                    << " failed, error code: " << errno;
     }
-    return KVStorageStatus::STORAGE_ERROR;
+    return -1;
   }
   unsigned char *file_data_ptr = file_data;
 
@@ -121,15 +125,15 @@ KVStorageStatus FileStorage::Load() {
       LOG(WARNING) << "close file " << file_path_
                    << " failed, error code: " << errno;
     }
-    return KVStorageStatus::STORAGE_ERROR;
+    return -1;
   }
   res = close(fd);
   if (res != 0) {
     LOG(WARNING) << "close file " << file_path_
                  << " failed, error code: " << errno;
-    return KVStorageStatus::STORAGE_ERROR;
+    return -1;
   }
-  return KVStorageStatus::STORAGE_SUCCESS;
+  return 0;
 }
 
 bool FileStorage::Insert(const std::string &key,
@@ -145,12 +149,12 @@ const std::vector<unsigned char> *FileStorage::Find(const std::string &key) {
   return &(iter->second);
 }
 
-KVStorageStatus FileStorage::Flush() {
+int FileStorage::Flush() {
   int fd = open(file_path_.c_str(), O_WRONLY | O_CREAT, 0600);
   if (fd < 0) {
     LOG(WARNING) << "open file " << file_path_
                  << " failed, error code:" << errno;
-    return KVStorageStatus::STORAGE_ERROR;
+    return -1;
   }
 
   const size_t int_size = sizeof(int32_t);
@@ -194,7 +198,7 @@ KVStorageStatus FileStorage::Flush() {
         LOG(WARNING) << "close file " << file_path_
                      << " failed, error code: " << errno;
       }
-      return KVStorageStatus::STORAGE_ERROR;
+      return -1;
     }
     remain_size -= buffer_size;
     buffer_ptr += buffer_size;
@@ -204,9 +208,9 @@ KVStorageStatus FileStorage::Flush() {
   if (res != 0) {
     LOG(WARNING) << "close file " << file_path_
                  << " failed, error code: " << errno;
-    return KVStorageStatus::STORAGE_ERROR;
+    return -1;
   }
-  return KVStorageStatus::STORAGE_SUCCESS;
+  return 0;
 }
 
 };  // namespace mace
diff --git a/mace/core/file_storage.h b/mace/core/file_storage.h
index 716cf336db31d705acf913c9c544a06953340f37..c29628cdd657d7a16d494128cfee908dfdc1f18f 100644
--- a/mace/core/file_storage.h
+++ b/mace/core/file_storage.h
@@ -18,11 +18,11 @@ class FileStorage : public KVStorage {
   explicit FileStorage(const std::string &file_path);
 
  public:
-  KVStorageStatus Load() override;
+  int Load() override;
   bool Insert(const std::string &key,
               const std::vector<unsigned char> &value) override;
   const std::vector<unsigned char> *Find(const std::string &key) override;
-  KVStorageStatus Flush() override;
+  int Flush() override;
 
  private:
   std::string file_path_;
diff --git a/mace/core/runtime/opencl/opencl_runtime.cc b/mace/core/runtime/opencl/opencl_runtime.cc
index 44be3e959ca265020789982fe4d5487011136978..43f51c69ae086eb29015f92b1f26d2bcc203573f 100644
--- a/mace/core/runtime/opencl/opencl_runtime.cc
+++ b/mace/core/runtime/opencl/opencl_runtime.cc
@@ -317,7 +317,7 @@ OpenCLRuntime::OpenCLRuntime(GPUPerfHint gpu_perf_hint,
     storage_ = kStorageFactory->CreateStorage(cl_compiled_file_name);
 
     if (platform_info_ != kCompiledProgramPlatform) {
-      if (storage_->Load() == KVStorageStatus::STORAGE_ERROR) {
+      if (storage_->Load() != 0) {
         LOG(FATAL) << "Load opencl compiled kernel file failed";
       }
     }
@@ -506,7 +506,7 @@ cl::Kernel OpenCLRuntime::BuildKernel(
 
 void OpenCLRuntime::SaveBuiltCLProgram() {
   if (program_map_changed_ && storage_ != nullptr) {
-    if (storage_->Flush() != KVStorageStatus::STORAGE_SUCCESS) {
+    if (storage_->Flush() != 0) {
       LOG(FATAL) << "Store opencl compiled kernel to file failed";
     }
     program_map_changed_ = false;
diff --git a/mace/public/mace_runtime.h b/mace/public/mace_runtime.h
index 09de430cd77a877a1a30bd4f64303cbad5d7f4aa..8acb1cace385a876e97d62a2c2563c0bd13bd497 100644
--- a/mace/public/mace_runtime.h
+++ b/mace/public/mace_runtime.h
@@ -31,19 +31,15 @@ enum GPUPriorityHint {
 
 enum CPUPowerOption { DEFAULT = 0, HIGH_PERFORMANCE = 1, BATTERY_SAVE = 2 };
 
-enum KVStorageStatus {
-  STORAGE_SUCCESS = 0,
-  STORAGE_FILE_NOT_EXIST = 1,
-  STORAGE_ERROR = 2
-};
-
 class KVStorage {
  public:
-  virtual KVStorageStatus Load() = 0;
+  // return: 0 for success, -1 for error
+  virtual int Load() = 0;
   virtual bool Insert(const std::string &key,
                       const std::vector<unsigned char> &value) = 0;
   virtual const std::vector<unsigned char> *Find(const std::string &key) = 0;
-  virtual KVStorageStatus Flush() = 0;
+  // return: 0 for success, -1 for error
+  virtual int Flush() = 0;
 };
 
 class KVStorageFactory {