diff --git a/init/service.cpp b/init/service.cpp
index 331cd88..00aa4d1 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -534,7 +534,7 @@
         LOG(ERROR) << name_ << ": failed to read from notification channel: " << byte.error();
     }
     cgroups_activated.Close();
-    if (!*byte) {
+    if (*byte != kCgroupsActivated) {
         LOG(FATAL) << "Service '" << name_  << "' failed to start due to a fatal error";
         _exit(EXIT_FAILURE);
     }
@@ -693,7 +693,7 @@
                          limit_percent_ != -1 || !limit_property_.empty();
         errno = -createProcessGroup(proc_attr_.uid, pid_, use_memcg);
         if (errno != 0) {
-            Result<void> result = cgroups_activated.Write(0);
+            Result<void> result = cgroups_activated.Write(kActivatingCgroupsFailed);
             if (!result.ok()) {
                 return Error() << "Sending notification failed: " << result.error();
             }
@@ -717,7 +717,7 @@
         LmkdRegister(name_, proc_attr_.uid, pid_, oom_score_adjust_);
     }
 
-    if (Result<void> result = cgroups_activated.Write(1); !result.ok()) {
+    if (Result<void> result = cgroups_activated.Write(kCgroupsActivated); !result.ok()) {
         return Error() << "Sending cgroups activated notification failed: " << result.error();
     }
 
diff --git a/init/service_utils.h b/init/service_utils.h
index 65a2012..228ae2b 100644
--- a/init/service_utils.h
+++ b/init/service_utils.h
@@ -32,6 +32,12 @@
 namespace android {
 namespace init {
 
+// Constants used by Service::Start() for communication between parent and child.
+enum ServiceCode : uint8_t {
+    kActivatingCgroupsFailed,
+    kCgroupsActivated,
+};
+
 class Descriptor {
   public:
     Descriptor(const std::string& name, android::base::unique_fd fd)