diff --git a/include/sys/syscall.h b/include/sys/syscall.h
index 50c4e9d9ddc..2c4b5b82f36 100644
--- a/include/sys/syscall.h
+++ b/include/sys/syscall.h
@@ -339,23 +339,24 @@
 #define SYS_fcntl                      (__SYS_filedesc + 3)
 #define SYS_lseek                      (__SYS_filedesc + 4)
 #define SYS_mmap                       (__SYS_filedesc + 5)
-#define SYS_open                       (__SYS_filedesc + 6)
-#define SYS_opendir                    (__SYS_filedesc + 7)
-#define SYS_readdir                    (__SYS_filedesc + 8)
-#define SYS_rewinddir                  (__SYS_filedesc + 9)
-#define SYS_seekdir                    (__SYS_filedesc + 10)
-#define SYS_stat                       (__SYS_filedesc + 11)
-#define SYS_fstat                      (__SYS_filedesc + 12)
-#define SYS_statfs                     (__SYS_filedesc + 13)
-#define SYS_fstatfs                    (__SYS_filedesc + 14)
-#define SYS_telldir                    (__SYS_filedesc + 15)
+#define SYS_munmap                     (__SYS_filedesc + 6)
+#define SYS_open                       (__SYS_filedesc + 7)
+#define SYS_opendir                    (__SYS_filedesc + 8)
+#define SYS_readdir                    (__SYS_filedesc + 9)
+#define SYS_rewinddir                  (__SYS_filedesc + 10)
+#define SYS_seekdir                    (__SYS_filedesc + 11)
+#define SYS_stat                       (__SYS_filedesc + 12)
+#define SYS_fstat                      (__SYS_filedesc + 13)
+#define SYS_statfs                     (__SYS_filedesc + 14)
+#define SYS_fstatfs                    (__SYS_filedesc + 15)
+#define SYS_telldir                    (__SYS_filedesc + 16)
 
 #if defined(CONFIG_PSEUDOFS_SOFTLINKS)
-#  define SYS_link                     (__SYS_filedesc + 16)
-#  define SYS_readlink                 (__SYS_filedesc + 17)
-#  define __SYS_pipes                  (__SYS_filedesc + 18)
+#  define SYS_link                     (__SYS_filedesc + 17)
+#  define SYS_readlink                 (__SYS_filedesc + 18)
+#  define __SYS_pipes                  (__SYS_filedesc + 19)
 #else
-#  define __SYS_pipes                  (__SYS_filedesc + 16)
+#  define __SYS_pipes                  (__SYS_filedesc + 17)
 #endif
 
 #if defined(CONFIG_PIPES) && CONFIG_DEV_PIPE_SIZE > 0
diff --git a/syscall/syscall.csv b/syscall/syscall.csv
index 4423f9a1867..7d0ef87e721 100644
--- a/syscall/syscall.csv
+++ b/syscall/syscall.csv
@@ -48,6 +48,7 @@
 "mkdir","sys/stat.h","!defined(CONFIG_DISABLE_MOUNTPOINT)","int","FAR const char*","mode_t"
 "mkfifo2","nuttx/drivers/drivers.h","defined(CONFIG_PIPES) && CONFIG_DEV_FIFO_SIZE > 0","int","FAR const char*","mode_t","size_t"
 "mmap","sys/mman.h","","FAR void*","FAR void*","size_t","int","int","int","off_t"
+"munmap","sys/mman.h","","int","FAR void*","size_t"
 "modhandle","nuttx/module.h","defined(CONFIG_MODULE)","FAR void *","FAR const char *"
 "mount","sys/mount.h","!defined(CONFIG_DISABLE_MOUNTPOINT) && defined(CONFIG_FS_READABLE)","int","const char*","const char*","const char*","unsigned long","const void*"
 "mq_close","mqueue.h","!defined(CONFIG_DISABLE_MQUEUE)","int","mqd_t"
diff --git a/syscall/syscall_lookup.h b/syscall/syscall_lookup.h
index 3786ce69d83..a7e0d770ca0 100644
--- a/syscall/syscall_lookup.h
+++ b/syscall/syscall_lookup.h
@@ -234,6 +234,7 @@ SYSCALL_LOOKUP(up_assert,                  2, STUB_up_assert)
   SYSCALL_LOOKUP(fcntl,                    6, STUB_fcntl)
   SYSCALL_LOOKUP(lseek,                    3, STUB_lseek)
   SYSCALL_LOOKUP(mmap,                     6, STUB_mmap)
+  SYSCALL_LOOKUP(munmap,                   2, STUB_munmap)
   SYSCALL_LOOKUP(open,                     6, STUB_open)
   SYSCALL_LOOKUP(opendir,                  1, STUB_opendir)
   SYSCALL_LOOKUP(readdir,                  1, STUB_readdir)
diff --git a/syscall/syscall_stublookup.c b/syscall/syscall_stublookup.c
index 0065e2ae21e..fd2e6484f53 100644
--- a/syscall/syscall_stublookup.c
+++ b/syscall/syscall_stublookup.c
@@ -244,6 +244,7 @@ uintptr_t STUB_lseek(int nbr, uintptr_t parm1, uintptr_t parm2,
 uintptr_t STUB_mmap(int nbr, uintptr_t parm1, uintptr_t parm2,
             uintptr_t parm3, uintptr_t parm4, uintptr_t parm5,
             uintptr_t parm6);
+uintptr_t STUB_munmap(int nbr, uintptr_t parm1, uintptr_t parm2);
 uintptr_t STUB_open(int nbr, uintptr_t parm1, uintptr_t parm2,
             uintptr_t parm3, uintptr_t parm4, uintptr_t parm5,
             uintptr_t parm6);