diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 182de17..0899264 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -126,6 +126,7 @@
 int mlock2(const void* addr, size_t len, int flags)    all
 int         munlock(const void* addr, size_t len)   all
 int         mlockall(int flags)   all
+int mseal(void*, size_t, unsigned long) lp64
 int         munlockall()   all
 int         mincore(void*  start, size_t  length, unsigned char*  vec)   all
 int         __ioctl:ioctl(int, int, void*)  all
diff --git a/libc/bionic/legacy_32_bit_support.cpp b/libc/bionic/legacy_32_bit_support.cpp
index 4e19ebf..e66126b 100644
--- a/libc/bionic/legacy_32_bit_support.cpp
+++ b/libc/bionic/legacy_32_bit_support.cpp
@@ -161,3 +161,9 @@
   }
   return __mremap(old_address, old_size, new_size, flags, new_address);
 }
+
+// mseal(2) is LP64-only.
+int mseal(void*, size_t, unsigned long) {
+  errno = ENOSYS;
+  return -1;
+}
diff --git a/libc/include/sys/mman.h b/libc/include/sys/mman.h
index 823c9ba..26d08c3 100644
--- a/libc/include/sys/mman.h
+++ b/libc/include/sys/mman.h
@@ -222,4 +222,16 @@
  */
 int posix_madvise(void* _Nonnull __addr, size_t __size, int __advice) __INTRODUCED_IN(23);
 
+/**
+ * [mseal(2)](https://man7.org/linux/man-pages/man2/mseal.2.html)
+ * seals the given range to prevent modifications such as mprotect() calls.
+ *
+ * Available since API level 36.
+ * Requires a Linux 6.10 or newer kernel.
+ * Always fails for 32-bit processes.
+ *
+ * Returns 0 on success, and returns -1 and sets `errno` on failure.
+ */
+int mseal(void* _Nonnull __addr, size_t __size, unsigned long __flags) __INTRODUCED_IN(36);
+
 __END_DECLS
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index ffd5d1e..8bb84eb 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -670,6 +670,7 @@
     mprotect;
     mrand48;
     mremap;
+    mseal; # introduced=36
     msync;
     munlock;
     munlockall;