diff --git a/include/limits.h b/include/limits.h
index b4502fa8bd..e5ae7a379c 100644
--- a/include/limits.h
+++ b/include/limits.h
@@ -82,7 +82,7 @@
  *
  * Required for sigqueue
  *
- *   _POSIX_RTSIG_MAX      Difference between SIGRTMIN and SIGRTMAX
+ *   _POSIX_RTSIG_MAX      Number of realtime signals reserved for application
  *   _POSIX_SIGQUEUE_MAX   Max number signals a task can queue
  *
  * Required for POSIX timers
@@ -146,7 +146,7 @@
 
 /* Required for sigqueue */
 
-#define _POSIX_RTSIG_MAX      31
+#define _POSIX_RTSIG_MAX      2    /*  Number of reserved realtime signals */
 #define _POSIX_SIGQUEUE_MAX   32
 
 /* Required for symbolic links */
diff --git a/include/signal.h b/include/signal.h
index 392b4cc323..109bf94efc 100644
--- a/include/signal.h
+++ b/include/signal.h
@@ -39,14 +39,15 @@
 
 #define NULL_SIGNAL_SET ((sigset_t)0x00000000)
 #define ALL_SIGNAL_SET  ((sigset_t)0xffffffff)
-#define MIN_SIGNO       1
-#define MAX_SIGNO       31
+#define MIN_SIGNO       1               /* Lowest valid signal number */
+#define MAX_SIGNO       31              /* Highest valid signal number */
 #define GOOD_SIGNO(s)   ((((unsigned)(s)) <= MAX_SIGNO))
 #define SIGNO2SET(s)    ((sigset_t)1 << (s))
 
-/* All signals are "real time" signals */
+/* Definitions for "real time" signals */
 
-#define SIGRTMIN        MIN_SIGNO       /* First real time signal */
+#define SIGSTDMAX       29              /* Last standard signal number */
+#define SIGRTMIN        (SIGSTDMAX + 1) /* First real time signal */
 #define SIGRTMAX        MAX_SIGNO       /* Last real time signal */
 #define _NSIG           (MAX_SIGNO + 1) /* Biggest signal number + 1 */