diff --git a/common/utils.cc b/common/utils.cc
index 1e04b61..1cb37e5 100644
--- a/common/utils.cc
+++ b/common/utils.cc
@@ -57,7 +57,6 @@
 #include "update_engine/common/prefs_interface.h"
 #include "update_engine/common/subprocess.h"
 #include "update_engine/payload_consumer/file_descriptor.h"
-#include "update_engine/payload_consumer/file_writer.h"
 #include "update_engine/payload_consumer/payload_constants.h"
 
 using base::Time;
@@ -189,14 +188,11 @@
   return "";
 }
 
-bool WriteFile(const char* path, const void* data, int data_len) {
-  DirectFileWriter writer;
-  TEST_AND_RETURN_FALSE_ERRNO(0 == writer.Open(path,
-                                               O_WRONLY | O_CREAT | O_TRUNC,
-                                               0600));
-  ScopedFileWriterCloser closer(&writer);
-  TEST_AND_RETURN_FALSE_ERRNO(writer.Write(data, data_len));
-  return true;
+bool WriteFile(const char* path, const void* data, size_t data_len) {
+  int fd = HANDLE_EINTR(open(path, O_WRONLY | O_CREAT | O_TRUNC, 0600));
+  TEST_AND_RETURN_FALSE_ERRNO(fd >= 0);
+  ScopedFdCloser fd_closer(&fd);
+  return WriteAll(fd, data, data_len);
 }
 
 bool ReadAll(
diff --git a/common/utils.h b/common/utils.h
index 3cffcdd..d551b7b 100644
--- a/common/utils.h
+++ b/common/utils.h
@@ -62,7 +62,7 @@
 
 // Writes the data passed to path. The file at path will be overwritten if it
 // exists. Returns true on success, false otherwise.
-bool WriteFile(const char* path, const void* data, int data_len);
+bool WriteFile(const char* path, const void* data, size_t data_len);
 
 // Calls write() or pwrite() repeatedly until all count bytes at buf are
 // written to fd or an error occurs. Returns true on success.
diff --git a/common/utils_unittest.cc b/common/utils_unittest.cc
index 634de01..7852910 100644
--- a/common/utils_unittest.cc
+++ b/common/utils_unittest.cc
@@ -52,6 +52,21 @@
   EXPECT_EQ("", utils::ParseECVersion("b=1231a fw_version a=fasd2"));
 }
 
+TEST(UtilsTest, WriteFileOpenFailure) {
+  EXPECT_FALSE(utils::WriteFile("/this/doesn't/exist", "hello", 5));
+}
+
+TEST(UtilsTest, WriteFileReadFile) {
+  base::FilePath file;
+  EXPECT_TRUE(base::CreateTemporaryFile(&file));
+  ScopedPathUnlinker unlinker(file.value());
+  EXPECT_TRUE(utils::WriteFile(file.value().c_str(), "hello", 5));
+
+  brillo::Blob readback;
+  EXPECT_TRUE(utils::ReadFile(file.value().c_str(), &readback));
+  EXPECT_EQ("hello", string(readback.begin(), readback.end()));
+}
+
 TEST(UtilsTest, ReadFileFailure) {
   brillo::Blob empty;
   EXPECT_FALSE(utils::ReadFile("/this/doesn't/exist", &empty));