diff --git a/include/ntapi/nt_string.h b/include/ntapi/nt_string.h
index 4fddf8f..059a7ee 100644
--- a/include/ntapi/nt_string.h
+++ b/include/ntapi/nt_string.h
@@ -9,7 +9,6 @@ typedef void * __cdecl ntapi_memset(
 	int c,
 	size_t count);
 
-
 typedef int __cdecl ntapi_sprintf(
 	char * buffer,
 	const char * format,
@@ -93,6 +92,9 @@ typedef uintptr_t * __cdecl	ntapi_tt_aligned_block_memcpy(
 	__in	const uintptr_t *	src,
 	__in	size_t			bytes);
 
+typedef void * __cdecl		ntapi_tt_aligned_block_memlock(
+	__in	void *			block,
+	__in	size_t			bytes);
 
 typedef wchar16_t * __cdecl	ntapi_tt_memcpy_utf16(
 	__in	wchar16_t *		dst,
diff --git a/include/ntapi/ntapi.h b/include/ntapi/ntapi.h
index c04d10a..8de63d3 100644
--- a/include/ntapi/ntapi.h
+++ b/include/ntapi/ntapi.h
@@ -458,6 +458,7 @@ typedef struct _ntapi_vtbl {
 	ntapi_tt_strncmp_utf16 *			tt_strncmp_utf16;
 	ntapi_tt_aligned_block_memset *			tt_aligned_block_memset;
 	ntapi_tt_aligned_block_memcpy *			tt_aligned_block_memcpy;
+	ntapi_tt_aligned_block_memlock *		tt_aligned_block_memlock;
 	ntapi_tt_aligned_memcpy_utf16 *			tt_aligned_memcpy_utf16;
 	ntapi_tt_memcpy_utf16 *				tt_memcpy_utf16;
 	ntapi_tt_generic_memset *			tt_generic_memset;
diff --git a/project/common.mk b/project/common.mk
index f30b611..7be6a79 100644
--- a/project/common.mk
+++ b/project/common.mk
@@ -97,6 +97,7 @@ COMMON_SRCS = \
 	src/socket/ntapi_sc_socket_v2.c \
 	src/socket/ntapi_sc_wait.c \
 	src/string/ntapi_tt_aligned_block_memcpy.c \
+	src/string/ntapi_tt_aligned_block_memlock.c \
 	src/string/ntapi_tt_aligned_block_memset.c \
 	src/string/ntapi_tt_aligned_memcpy_utf16.c \
 	src/string/ntapi_tt_hex_utf16_to_uintptr.c \
diff --git a/src/internal/ntapi.c b/src/internal/ntapi.c
index 9361338..a53ca80 100644
--- a/src/internal/ntapi.c
+++ b/src/internal/ntapi.c
@@ -253,6 +253,7 @@ static int32_t __fastcall __ntapi_init_once(ntapi_vtbl ** pvtbl)
 	__ntapi->tt_strncmp_utf16				= __ntapi_tt_strncmp_utf16;
 	__ntapi->tt_aligned_block_memset 			= __ntapi_tt_aligned_block_memset;
 	__ntapi->tt_aligned_block_memcpy 			= __ntapi_tt_aligned_block_memcpy;
+	__ntapi->tt_aligned_block_memlock 			= __ntapi_tt_aligned_block_memlock;
 	__ntapi->tt_memcpy_utf16 				= __ntapi_tt_memcpy_utf16;
 	__ntapi->tt_aligned_memcpy_utf16 			= __ntapi_tt_aligned_memcpy_utf16;
 	__ntapi->tt_generic_memset				= __ntapi_tt_generic_memset;
diff --git a/src/internal/ntapi_fnapi.h b/src/internal/ntapi_fnapi.h
index 7c744c9..8280f55 100644
--- a/src/internal/ntapi_fnapi.h
+++ b/src/internal/ntapi_fnapi.h
@@ -115,6 +115,7 @@ ntapi_tt_strncmp_multibyte			__ntapi_tt_strncmp_multibyte;
 ntapi_tt_strncmp_utf16				__ntapi_tt_strncmp_utf16;
 ntapi_tt_aligned_block_memset			__ntapi_tt_aligned_block_memset;
 ntapi_tt_aligned_block_memcpy			__ntapi_tt_aligned_block_memcpy;
+ntapi_tt_aligned_block_memlock			__ntapi_tt_aligned_block_memlock;
 ntapi_tt_init_unicode_string_from_utf16		__ntapi_tt_init_unicode_string_from_utf16;
 ntapi_tt_memcpy_utf16				__ntapi_tt_memcpy_utf16;
 ntapi_tt_aligned_memcpy_utf16			__ntapi_tt_aligned_memcpy_utf16;
diff --git a/src/string/ntapi_tt_aligned_block_memlock.c b/src/string/ntapi_tt_aligned_block_memlock.c
new file mode 100644
index 0000000..5aa3a7e
--- /dev/null
+++ b/src/string/ntapi_tt_aligned_block_memlock.c
@@ -0,0 +1,23 @@
+/********************************************************/
+/*  ntapi: Native API core library                      */
+/*  Copyright (C) 2013--2018  Z. Gilboa                 */
+/*  Released under GPLv2 and GPLv3; see COPYING.NTAPI.  */
+/********************************************************/
+
+#include <psxtypes/psxtypes.h>
+#include <ntapi/nt_string.h>
+#include <ntapi/nt_sync.h>
+#include <ntapi/nt_atomic.h>
+
+uintptr_t * __cdecl __ntapi_tt_aligned_block_memlock(
+	__in	uintptr_t *	dst,
+	__in	size_t		bytes)
+{
+	size_t addr = (size_t)dst & ~(size_t)(NT_SYNC_BLOCK_SIZE);
+	size_t cap  = addr + bytes;
+
+	for (; addr<cap; addr+=NT_SYNC_BLOCK_SIZE)
+		at_locked_xadd((intptr_t *)addr,0);
+
+	return dst;
+}