diff --git a/src/jrd/thd.cpp b/src/jrd/thd.cpp
index 4d5393a3c1..2ff62eec94 100644
--- a/src/jrd/thd.cpp
+++ b/src/jrd/thd.cpp
@@ -153,7 +153,7 @@ int THD_rec_mutex_unlock(REC_MUTX_T * rec_mutex)
 	}
 	return 0;
 }
-#endif /* SUPERSERVER */
+#endif // SUPERSERVER
 
 
 #ifdef WIN_NT
@@ -309,7 +309,7 @@ void THD_yield(void)
 	sched_yield();
 #else
 	pthread_yield();
-#endif /* _POSIX_PRIORITY_SCHEDULING */
+#endif // _POSIX_PRIORITY_SCHEDULING
 #endif
 
 #ifdef SOLARIS_MT
@@ -319,5 +319,5 @@ void THD_yield(void)
 #ifdef WIN_NT
 	SleepEx(0, FALSE);
 #endif
-#endif /* MULTI_THREAD */
+#endif // MULTI_THREAD
 }
diff --git a/src/jrd/thd.h b/src/jrd/thd.h
index 088696d44b..ce6dc5723a 100644
--- a/src/jrd/thd.h
+++ b/src/jrd/thd.h
@@ -50,7 +50,7 @@ inline void	THD_mutex_lock_global(void) {
 inline void THD_mutex_unlock_global(void) {
 	global_mutex.leave();
 }
-#endif
+#endif // MULTI_THREAD
 
 // recursive mutex
 #ifdef SUPERSERVER
@@ -186,12 +186,12 @@ typedef rec_mutx_t REC_MUTX_T;
 #define THD_GLOBAL_MUTEX_UNLOCK		THD_mutex_unlock_global()
 #define THD_MUTEX_LOCK(mutx)		THD_mutex_lock(mutx)
 #define THD_MUTEX_UNLOCK(mutx)		THD_mutex_unlock(mutx)
-#else
+#else // MULTI_THREAD
 #define THD_GLOBAL_MUTEX_LOCK
 #define THD_GLOBAL_MUTEX_UNLOCK
 #define THD_MUTEX_LOCK(mutx)
 #define THD_MUTEX_UNLOCK(mutx)
-#endif
+#endif // MULTI_THREAD
 
 extern "C" {
 	int		API_ROUTINE gds__thread_start(ThreadEntryPoint*, void*, int, int,