diff --git a/ChangeLog b/ChangeLog
index 2494344..0531a84 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,7 @@
    * PSK and DHE-PSK based ciphersuites added
    * Memory allocation abstraction layer added
    * Buffer-based memory allocator added (no malloc() / free() / HEAP usage)
+   * Threading abstraction layer added (dummy / pthread / alternate)
    * Public Key abstraction layer added
    * Parsing Elliptic Curve keys
    * Parsing Elliptic Curve certificates
diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index f2ac41c..4a9d0ef 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -660,6 +660,39 @@
 #define POLARSSL_SSL_TRUNCATED_HMAC
 
 /**
+ * \def POLARSSL_THREADING_ALT
+ *
+ * Provide your own alternate threading implementation.
+ *
+ * Requires: POLARSSL_THREADING_C
+ *
+ * Uncomment this to allow your own alternate threading implementation.
+#define POLARSSL_THREADING_ALT
+ */
+
+/**
+ * \def POLARSSL_THREADING_DUMMY
+ *
+ * Provide a dummy threading implementation.
+ *
+ * Requires: POLARSSL_THREADING_C
+ *
+ * Uncomment this to enable code to compile like with threading enabled
+#define POLARSSL_THREADING_DUMMY
+ */
+
+/**
+ * \def POLARSSL_THREADING_PTHREAD
+ *
+ * Enable the pthread wrapper layer for the threading layer.
+ *
+ * Requires: POLARSSL_THREADING_C
+ *
+ * Uncomment this to enable pthread mutexes.
+#define POLARSSL_THREADING_PTHREAD
+ */
+
+/**
  * \def POLARSSL_X509_ALLOW_EXTENSIONS_NON_V3
  *
  * If set, the X509 parser will not break-off when parsing an X509 certificate
@@ -1436,6 +1469,27 @@
 #define POLARSSL_SSL_TLS_C
 
 /**
+ * \def POLARSSL_THREADING_C
+ *
+ * Enable the threading abstraction layer.
+ * By default PolarSSL assumes it is used in a non-threaded environment or that
+ * contexts are not shared between threads. If you do intend to use contexts
+ * between threads, you will need to enable this layer to prevent race
+ * conditions.
+ *
+ * Module:  library/threading.c
+ *
+ * This allows different threading implementations (self-implemented or
+ * provided).
+ *
+ * You will have to enable either POLARSSL_THREADING_ALT,
+ * POLARSSL_THREADING_PTHREAD or POLARSSL_THREADING_DUMMY.
+ *
+ * Enable this layer to allow use of mutexes within PolarSSL
+#define POLARSSL_THREADING_C
+ */
+
+/**
  * \def POLARSSL_TIMING_C
  *
  * Enable the portable timing interface.
@@ -1784,6 +1838,32 @@
 #error "POLARSSL_SSL_SESSION_TICKETS_C defined, but not all prerequisites"
 #endif
 
+#if defined(POLARSSL_THREADING_DUMMY)
+#if !defined(POLARSSL_THREADING_C) || defined(POLARSSL_THREADING_IMPL)
+#error "POLARSSL_THREADING_DUMMY defined, but not all prerequisites"
+#endif
+#define POLARSSL_THREADING_IMPL
+#endif
+
+#if defined(POLARSSL_THREADING_PTHREAD)
+#if !defined(POLARSSL_THREADING_C) || defined(POLARSSL_THREADING_IMPL)
+#error "POLARSSL_THREADING_PTHREAD defined, but not all prerequisites"
+#endif
+#define POLARSSL_THREADING_IMPL
+#endif
+
+#if defined(POLARSSL_THREADING_ALT)
+#if !defined(POLARSSL_THREADING_C) || defined(POLARSSL_THREADING_IMPL)
+#error "POLARSSL_THREADING_ALT defined, but not all prerequisites"
+#endif
+#define POLARSSL_THREADING_IMPL
+#endif
+
+#if defined(POLARSSL_THREADING_C) && !defined(POLARSSL_THREADING_IMPL)
+#error "POLARSSL_THREADING_C defined, single threading implementation required"
+#endif
+#undef POLARSSL_THREADING_IMPL
+
 #if defined(POLARSSL_X509_USE_C) && ( !defined(POLARSSL_BIGNUM_C) ||  \
     !defined(POLARSSL_OID_C) || !defined(POLARSSL_ASN1_PARSE_C) ||      \
     !defined(POLARSSL_PK_PARSE_C) )
diff --git a/include/polarssl/error.h b/include/polarssl/error.h
index ab3d632..a64960c 100644
--- a/include/polarssl/error.h
+++ b/include/polarssl/error.h
@@ -53,6 +53,7 @@
  * MPI       7  0x0002-0x0010
  * GCM       2  0x0012-0x0014
  * BLOWFISH  2  0x0016-0x0018
+ * THREADING 3  0x001A-0x001E
  * AES       2  0x0020-0x0022
  * CAMELLIA  2  0x0024-0x0026
  * XTEA      1  0x0028-0x0028
diff --git a/include/polarssl/threading.h b/include/polarssl/threading.h
new file mode 100644
index 0000000..4afaeea
--- /dev/null
+++ b/include/polarssl/threading.h
@@ -0,0 +1,84 @@
+/**
+ * \file threading.h
+ *
+ * \brief Threading abstraction layer
+ *
+ *  Copyright (C) 2006-2013, Brainspark B.V.
+ *
+ *  This file is part of PolarSSL (http://www.polarssl.org)
+ *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
+ *
+ *  All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef POLARSSL_THREADING_H
+#define POLARSSL_THREADING_H
+
+#include "config.h"
+
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define POLARSSL_ERR_THREADING_FEATURE_UNAVAILABLE         -0x001A  /**< The selected feature is not available. */
+#define POLARSSL_ERR_THREADING_BAD_INPUT_DATA              -0x001C  /**< Bad input parameters to function. */
+#define POLARSSL_ERR_THREADING_MUTEX_ERROR                 -0x001E  /**< Locking / unlocking / free failed with error code. */
+
+#if defined(POLARSSL_THREADING_DUMMY)
+typedef void threading_mutex_t;
+#endif
+
+#if defined(POLARSSL_THREADING_PTHREAD)
+#include <pthread.h>
+typedef pthread_mutex_t threading_mutex_t;
+#endif
+
+#if defined(POLARSSL_THREADING_ALT)
+/* You should define the threading_mutex_t type in your header */
+#include "threading_alt.h"
+
+/**
+ * \brief           Set your alternate threading implementation function
+ *                  pointers
+ *
+ * \param mutex_init    the malloc function implementation
+ * \param mutex_free    the free function implementation
+ * \param mutex_lock    the lock function implementation
+ * \param mutex_unlock  the unlock function implementation
+ *
+ * \return              0 if successful
+ */
+int threading_set_alt( int (*mutex_init)( threading_mutex_t * ),
+                       int (*mutex_free)( threading_mutex_t * ),
+                       int (*mutex_lock)( threading_mutex_t * ),
+                       int (*mutex_unlock)( threading_mutex_t * ) );
+#endif /* POLARSSL_THREADING_ALT_C */
+
+/*
+ * The function pointers for mutex_init, mutex_free, mutex_ and mutex_unlock
+ */
+extern int (*polarssl_mutex_init)( threading_mutex_t *mutex );
+extern int (*polarssl_mutex_free)( threading_mutex_t *mutex );
+extern int (*polarssl_mutex_lock)( threading_mutex_t *mutex );
+extern int (*polarssl_mutex_unlock)( threading_mutex_t *mutex );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* threading.h */
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index dda7ff1..bc22f26 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -52,6 +52,7 @@
      ssl_cli.c
      ssl_srv.c
      ssl_tls.c
+     threading.c
      timing.c
      version.c
      x509.c
diff --git a/library/Makefile b/library/Makefile
index 003b933..4c37adf 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -54,7 +54,8 @@
 		rsa.o		sha1.o		sha256.o		\
 		sha512.o	ssl_cache.o	ssl_cli.o		\
 		ssl_srv.o   ssl_ciphersuites.o			\
-		ssl_tls.o	timing.o	version.o		\
+		ssl_tls.o	threading.o	timing.o		\
+		version.o								\
 		x509.o		x509_create.o				\
 		x509_crl.o	x509_crt.o	x509_csr.o		\
 		x509write_crt.o			x509write_csr.o	\
diff --git a/library/error.c b/library/error.c
index 8506897..a7e1467 100644
--- a/library/error.c
+++ b/library/error.c
@@ -145,6 +145,10 @@
 #include "polarssl/ssl.h"
 #endif
 
+#if defined(POLARSSL_THREADING_C)
+#include "polarssl/threading.h"
+#endif
+
 #if defined(POLARSSL_X509_USE_C) || defined(POLARSSL_X509_CREATE_C)
 #include "polarssl/x509.h"
 #endif
@@ -647,6 +651,15 @@
         snprintf( buf, buflen, "SHA512 - Read/write error in file" );
 #endif /* POLARSSL_SHA512_C */
 
+#if defined(POLARSSL_THREADING_C)
+    if( use_ret == -(POLARSSL_ERR_THREADING_FEATURE_UNAVAILABLE) )
+        snprintf( buf, buflen, "THREADING - The selected feature is not available" );
+    if( use_ret == -(POLARSSL_ERR_THREADING_BAD_INPUT_DATA) )
+        snprintf( buf, buflen, "THREADING - Bad input parameters to function" );
+    if( use_ret == -(POLARSSL_ERR_THREADING_MUTEX_ERROR) )
+        snprintf( buf, buflen, "THREADING - Locking / unlocking / free failed with error code" );
+#endif /* POLARSSL_THREADING_C */
+
 #if defined(POLARSSL_XTEA_C)
     if( use_ret == -(POLARSSL_ERR_XTEA_INVALID_INPUT_LENGTH) )
         snprintf( buf, buflen, "XTEA - The data input has an invalid length" );
diff --git a/library/threading.c b/library/threading.c
new file mode 100644
index 0000000..e79348a
--- /dev/null
+++ b/library/threading.c
@@ -0,0 +1,134 @@
+/*
+ *  Threading abstraction layer
+ *
+ *  Copyright (C) 2006-2013, Brainspark B.V.
+ *
+ *  This file is part of PolarSSL (http://www.polarssl.org)
+ *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
+ *
+ *  All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "polarssl/config.h"
+
+#if defined(POLARSSL_THREADING_C)
+
+#include "polarssl/threading.h"
+
+#if defined(POLARSSL_THREADING_DUMMY)
+static int threading_mutex_init_dummy( threading_mutex_t *mutex )
+{
+    ((void) mutex );
+    return( 0 );
+}
+
+static int threading_mutex_free_dummy( threading_mutex_t *mutex )
+{
+    ((void) mutex );
+    return( 0 );
+}
+
+static int threading_mutex_lock_dummy( threading_mutex_t *mutex )
+{
+    ((void) mutex );
+    return( 0 );
+}
+
+static int threading_mutex_unlock_dummy( threading_mutex_t *mutex )
+{
+    ((void) mutex );
+    return( 0 );
+}
+
+int (*polarssl_mutex_init)( threading_mutex_t * ) = threading_mutex_init_dummy;
+int (*polarssl_mutex_free)( threading_mutex_t * ) = threading_mutex_free_dummy;
+int (*polarssl_mutex_lock)( threading_mutex_t * ) = threading_mutex_lock_dummy;
+int (*polarssl_mutex_unlock)( threading_mutex_t * ) = threading_mutex_unlock_dummy;
+#endif /* POLARSSL_THREADING_DUMMY */
+
+#if defined(POLARSSL_THREADING_PTHREAD)
+static int threading_mutex_init_pthread( threading_mutex_t *mutex )
+{
+    if( mutex == NULL )
+        return( POLARSSL_ERR_THREADING_BAD_INPUT_DATA );
+
+    if( pthread_mutex_init( mutex, NULL ) != 0 )
+        return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
+
+    return( 0 );
+}
+
+static int threading_mutex_free_pthread( threading_mutex_t *mutex )
+{
+    if( mutex == NULL )
+        return( POLARSSL_ERR_THREADING_BAD_INPUT_DATA );
+
+    if( pthread_mutex_destroy( mutex ) != 0 )
+        return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
+
+    return( 0 );
+}
+
+static int threading_mutex_lock_pthread( threading_mutex_t *mutex )
+{
+    if( mutex == NULL )
+        return( POLARSSL_ERR_THREADING_BAD_INPUT_DATA );
+
+    if( pthread_mutex_lock( mutex ) != 0 )
+        return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
+
+    return( 0 );
+}
+
+static int threading_mutex_unlock_pthread( threading_mutex_t *mutex )
+{
+    if( mutex == NULL )
+        return( POLARSSL_ERR_THREADING_BAD_INPUT_DATA );
+
+    if( pthread_mutex_unlock( mutex ) != 0 )
+        return( POLARSSL_ERR_THREADING_MUTEX_ERROR );
+
+    return( 0 );
+}
+
+int (*polarssl_mutex_init)( threading_mutex_t * ) = threading_mutex_init_pthread;
+int (*polarssl_mutex_free)( threading_mutex_t * ) = threading_mutex_free_pthread;
+int (*polarssl_mutex_lock)( threading_mutex_t * ) = threading_mutex_lock_pthread;
+int (*polarssl_mutex_unlock)( threading_mutex_t * ) = threading_mutex_unlock_pthread;
+#endif /* POLARSSL_THREADING_PTHREAD */
+
+#if defined(POLARSSL_THREADING_ALT)
+int (*polarssl_mutex_init)( threading_mutex_t * ) = NULL;
+int (*polarssl_mutex_free)( threading_mutex_t * ) = NULL;
+int (*polarssl_mutex_lock)( threading_mutex_t * ) = NULL;
+int (*polarssl_mutex_unlock)( threading_mutex_t * ) = NULL;
+
+int threading_set_own( int (*mutex_init)( threading_mutex_t * ),
+                       int (*mutex_free)( threading_mutex_t * ),
+                       int (*mutex_lock)( threading_mutex_t * ),
+                       int (*mutex_unlock)( threading_mutex_t * ) )
+{
+    polarssl_mutex_init = mutex_init;
+    polarssl_mutex_free = mutex_free;
+    polarssl_mutex_lock = mutex_lock;
+    polarssl_mutex_unlock = mutex_unlock;
+
+    return( 0 );
+}
+#endif /* POLARSSL_THREADING_ALT_C */
+
+#endif /* POLARSSL_THREADING_C */
diff --git a/scripts/generate_errors.pl b/scripts/generate_errors.pl
index 85dde35..0dff537 100755
--- a/scripts/generate_errors.pl
+++ b/scripts/generate_errors.pl
@@ -11,7 +11,8 @@
 my @low_level_modules = ( "AES", "ASN1", "BLOWFISH", "CAMELLIA", "BIGNUM",
                           "BASE64", "XTEA", "PBKDF2", "OID",
                           "PADLOCK", "DES", "NET", "CTR_DRBG", "ENTROPY",
-                          "MD2", "MD4", "MD5", "SHA1", "SHA256", "SHA512", "GCM" );
+                          "MD2", "MD4", "MD5", "SHA1", "SHA256", "SHA512",
+                          "GCM", "THREADING" );
 my @high_level_modules = ( "PEM", "X509", "DHM", "RSA", "ECP", "MD", "CIPHER", "SSL",
                            "PK", "PKCS12", "PKCS5" );