diff --git a/init/service.cpp b/init/service.cpp
index f67af2d..44d9d8c 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -850,7 +850,7 @@
     return nullptr;
 }
 
-void ServiceManager::ForEachService(std::function<void(Service*)> callback) const {
+void ServiceManager::ForEachService(const std::function<void(Service*)>& callback) const {
     for (const auto& s : services_) {
         callback(s.get());
     }
diff --git a/init/service.h b/init/service.h
index aa73aaf..fb03a07 100644
--- a/init/service.h
+++ b/init/service.h
@@ -177,7 +177,7 @@
     Service* FindServiceByName(const std::string& name) const;
     Service* FindServiceByPid(pid_t pid) const;
     Service* FindServiceByKeychord(int keychord_id) const;
-    void ForEachService(std::function<void(Service*)> callback) const;
+    void ForEachService(const std::function<void(Service*)>& callback) const;
     void ForEachServiceInClass(const std::string& classname,
                                void (*func)(Service* svc)) const;
     void ForEachServiceWithFlags(unsigned matchflags,
diff --git a/init/util.cpp b/init/util.cpp
index 6c1923f..10ab1c7 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -317,7 +317,7 @@
 }
 
 void import_kernel_cmdline(bool in_qemu,
-                           std::function<void(const std::string&, const std::string&, bool)> fn) {
+                           const std::function<void(const std::string&, const std::string&, bool)>& fn) {
     std::string cmdline;
     android::base::ReadFileToString("/proc/cmdline", &cmdline);
 
diff --git a/init/util.h b/init/util.h
index 9d522cc..f020da8 100644
--- a/init/util.h
+++ b/init/util.h
@@ -55,7 +55,7 @@
 void remove_link(const char *oldpath, const char *newpath);
 int wait_for_file(const char *filename, int timeout);
 void import_kernel_cmdline(bool in_qemu,
-                           std::function<void(const std::string&, const std::string&, bool)>);
+                           const std::function<void(const std::string&, const std::string&, bool)>&);
 int make_dir(const char *path, mode_t mode);
 int restorecon(const char *pathname);
 int restorecon_recursive(const char *pathname);