diff --git a/delta_performer.cc b/delta_performer.cc
index 6094c5a..2538329 100644
--- a/delta_performer.cc
+++ b/delta_performer.cc
@@ -877,7 +877,7 @@
                                                        &output_positions));
 
   string temp_filename;
-  TEST_AND_RETURN_FALSE(utils::MakeTempFile("/tmp/au_patch.XXXXXX",
+  TEST_AND_RETURN_FALSE(utils::MakeTempFile("au_patch.XXXXXX",
                                             &temp_filename,
                                             nullptr));
   ScopedPathUnlinker path_unlinker(temp_filename);
@@ -943,7 +943,7 @@
                                                        &output_positions));
 
   string temp_filename;
-  TEST_AND_RETURN_FALSE(utils::MakeTempFile("/tmp/au_patch.XXXXXX",
+  TEST_AND_RETURN_FALSE(utils::MakeTempFile("au_patch.XXXXXX",
                                             &temp_filename,
                                             nullptr));
   ScopedPathUnlinker path_unlinker(temp_filename);
diff --git a/fake_p2p_manager_configuration.h b/fake_p2p_manager_configuration.h
index f639851..6874efb 100644
--- a/fake_p2p_manager_configuration.h
+++ b/fake_p2p_manager_configuration.h
@@ -35,7 +35,7 @@
 class FakeP2PManagerConfiguration : public P2PManager::Configuration {
  public:
   FakeP2PManagerConfiguration() {
-    EXPECT_TRUE(utils::MakeTempDirectory("/tmp/p2p-tc.XXXXXX", &p2p_dir_));
+    EXPECT_TRUE(utils::MakeTempDirectory("p2p-tc.XXXXXX", &p2p_dir_));
   }
 
   ~FakeP2PManagerConfiguration() {
diff --git a/postinstall_runner_action.cc b/postinstall_runner_action.cc
index 184d66d..c6879d8 100644
--- a/postinstall_runner_action.cc
+++ b/postinstall_runner_action.cc
@@ -48,8 +48,8 @@
   ScopedActionCompleter completer(processor_, this);
 
   // Make mountpoint.
-  TEST_AND_RETURN(utils::MakeTempDirectory("/tmp/au_postint_mount.XXXXXX",
-                                           &temp_rootfs_dir_));
+  TEST_AND_RETURN(
+      utils::MakeTempDirectory("au_postint_mount.XXXXXX", &temp_rootfs_dir_));
   ScopedDirRemover temp_dir_remover(temp_rootfs_dir_);
 
   const string mountable_device =
diff --git a/test_utils.h b/test_utils.h
index 7a77299..6108b6f 100644
--- a/test_utils.h
+++ b/test_utils.h
@@ -162,7 +162,7 @@
 class ScopedTempFile {
  public:
   ScopedTempFile() {
-    EXPECT_TRUE(utils::MakeTempFile("/tmp/update_engine_test_temp_file.XXXXXX",
+    EXPECT_TRUE(utils::MakeTempFile("update_engine_test_temp_file.XXXXXX",
                                     &path_,
                                     nullptr));
     unlinker_.reset(new ScopedPathUnlinker(path_));
diff --git a/utils.cc b/utils.cc
index cf7913c..6290478 100644
--- a/utils.cc
+++ b/utils.cc
@@ -130,6 +130,23 @@
   }
 }
 
+// If |path| is absolute, or explicit relative to the current working directory,
+// leaves it as is. Otherwise, uses the system's temp directory, as defined by
+// base::GetTempDir() and prepends it to |path|. On success stores the full
+// temporary path in |template_path| and returns true.
+bool GetTempName(const string& path, base::FilePath* template_path) {
+  if (path[0] == '/' || base::StartsWithASCII(path, "./", true) ||
+      base::StartsWithASCII(path, "../", true)) {
+    *template_path = base::FilePath(path);
+    return true;
+  }
+
+  base::FilePath temp_dir;
+  TEST_AND_RETURN_FALSE(base::GetTempDir(&temp_dir));
+  *template_path = temp_dir.Append(path);
+  return true;
+}
+
 }  // namespace
 
 namespace utils {
@@ -565,28 +582,17 @@
   return FileExists(volume_path.c_str());
 }
 
-// If |path| is absolute, or explicit relative to the current working directory,
-// leaves it as is. Otherwise, if TMPDIR is defined in the environment and is
-// non-empty, prepends it to |path|. Otherwise, prepends /tmp.  Returns the
-// resulting path.
-static const string PrependTmpdir(const string& path) {
-  if (path[0] == '/' || base::StartsWithASCII(path, "./", true) ||
-      base::StartsWithASCII(path, "../", true))
-    return path;
-
-  const char *tmpdir = getenv("TMPDIR");
-  const string prefix = (tmpdir && *tmpdir ? tmpdir : "/tmp");
-  return prefix + "/" + path;
-}
-
 bool MakeTempFile(const string& base_filename_template,
                   string* filename,
                   int* fd) {
-  const string filename_template = PrependTmpdir(base_filename_template);
+  base::FilePath filename_template;
+  TEST_AND_RETURN_FALSE(
+      GetTempName(base_filename_template, &filename_template));
   DCHECK(filename || fd);
-  vector<char> buf(filename_template.size() + 1);
-  memcpy(buf.data(), filename_template.data(), filename_template.size());
-  buf[filename_template.size()] = '\0';
+  vector<char> buf(filename_template.value().size() + 1);
+  memcpy(buf.data(), filename_template.value().data(),
+         filename_template.value().size());
+  buf[filename_template.value().size()] = '\0';
 
   int mkstemp_fd = mkstemp(buf.data());
   TEST_AND_RETURN_FALSE_ERRNO(mkstemp_fd >= 0);
@@ -603,11 +609,13 @@
 
 bool MakeTempDirectory(const string& base_dirname_template,
                        string* dirname) {
-  const string dirname_template = PrependTmpdir(base_dirname_template);
+  base::FilePath dirname_template;
+  TEST_AND_RETURN_FALSE(GetTempName(base_dirname_template, &dirname_template));
   DCHECK(dirname);
-  vector<char> buf(dirname_template.size() + 1);
-  memcpy(buf.data(), dirname_template.data(), dirname_template.size());
-  buf[dirname_template.size()] = '\0';
+  vector<char> buf(dirname_template.value().size() + 1);
+  memcpy(buf.data(), dirname_template.value().data(),
+         dirname_template.value().size());
+  buf[dirname_template.value().size()] = '\0';
 
   char* return_code = mkdtemp(buf.data());
   TEST_AND_RETURN_FALSE_ERRNO(return_code != nullptr);
diff --git a/utils.h b/utils.h
index 6668c39..252feab 100644
--- a/utils.h
+++ b/utils.h
@@ -131,9 +131,8 @@
 
 // If |base_filename_template| is neither absolute (starts with "/") nor
 // explicitly relative to the current working directory (starts with "./" or
-// "../"), then it is prepended the value of TMPDIR, which defaults to /tmp if
-// it isn't set or is empty.  It then calls mkstemp(3) with the resulting
-// template.  Writes the name of a new temporary file to |filename|. If |fd| is
+// "../"), then it is prepended the system's temporary directory. On success,
+// stores the name of the new temporary file in |filename|. If |fd| is
 // non-null, the file descriptor returned by mkstemp is written to it and
 // kept open; otherwise, it is closed. The template must end with "XXXXXX".
 // Returns true on success.
@@ -141,12 +140,11 @@
                   std::string* filename,
                   int* fd);
 
-// If |base_filename_template| is neither absolute (starts with "/") nor
+// If |base_dirname_template| is neither absolute (starts with "/") nor
 // explicitly relative to the current working directory (starts with "./" or
-// "../"), then it is prepended the value of TMPDIR, which defaults to /tmp if
-// it isn't set or is empty.  It then calls mkdtemp() with the resulting
-// template. Writes the name of the new temporary directory to |dirname|.
-// The template must end with "XXXXXX". Returns true on success.
+// "../"), then it is prepended the system's temporary directory. On success,
+// stores the name of the new temporary directory in |dirname|. The template
+// must end with "XXXXXX". Returns true on success.
 bool MakeTempDirectory(const std::string& base_dirname_template,
                        std::string* dirname);