diff --git a/ChangeLog b/ChangeLog
index 518650373..6928c8677 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -21,6 +21,7 @@ Features
      example application (programs/ssl/o_p_test) (Requires OpenSSL)
    * Added X509 CA Path support
    * Added Thumb assembly optimizations
+   * Added DEFLATE compression support as per RFC3749 (requires zlib)
 
 Changes
    * Removed redundant POLARSSL_DEBUG_MSG define
diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index a14e27124..a336067dd 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -248,6 +248,22 @@
  *
 #define POLARSSL_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION
  */
+
+/**
+ * \def POLARSSL_ZLIB_SUPPORT
+ *
+ * If set, the SSL/TLS module uses ZLIB to support compression and
+ * decompression of packet data.
+ *
+ * Used in: library/ssl_tls.c
+ *          library/ssl_cli.c
+ *          library/ssl_srv.c
+ *
+ * This feature requires zlib library and headers to be present.
+ *
+ * Uncomment to enable use of ZLIB
+#define POLARSSL_ZLIB_SUPPORT
+ */
 /* \} name */
 
 /**
diff --git a/include/polarssl/error.h b/include/polarssl/error.h
index fb739b187..508546eca 100644
--- a/include/polarssl/error.h
+++ b/include/polarssl/error.h
@@ -75,7 +75,7 @@
  * RSA      4   9
  * MD       5   4
  * CIPHER   6   5
- * SSL      6   1 (Started from top)
+ * SSL      6   2 (Started from top)
  * SSL      7   31
  *
  * Module dependent error code (5 bits 0x.08.-0x.F8.)
diff --git a/include/polarssl/ssl.h b/include/polarssl/ssl.h
index 1d7e7fd3f..40a57a7dc 100644
--- a/include/polarssl/ssl.h
+++ b/include/polarssl/ssl.h
@@ -43,6 +43,10 @@
 #include "pkcs11.h"
 #endif
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+#include "zlib.h"
+#endif
+
 #if defined(_MSC_VER) && !defined(inline)
 #define inline _inline
 #else
@@ -86,6 +90,7 @@
 #define POLARSSL_ERR_SSL_MALLOC_FAILED                     -0x7F00  /**< Memory allocation failed */
 #define POLARSSL_ERR_SSL_HW_ACCEL_FAILED                   -0x7F80  /**< Hardware acceleration function returned with error */
 #define POLARSSL_ERR_SSL_HW_ACCEL_FALLTHROUGH              -0x6F80  /**< Hardware acceleration function skipped / left alone data */
+#define POLARSSL_ERR_SSL_COMPRESSION_FAILED                -0x6F00  /**< Processing of the compression / decompression failed */
 
 /*
  * Various constants
@@ -99,6 +104,7 @@
 #define SSL_IS_CLIENT                   0
 #define SSL_IS_SERVER                   1
 #define SSL_COMPRESS_NULL               0
+#define SSL_COMPRESS_DEFLATE            1
 
 #define SSL_VERIFY_NONE                 0
 #define SSL_VERIFY_OPTIONAL             1
@@ -108,9 +114,17 @@
 
 /*
  * Allow an extra 512 bytes for the record header
- * and encryption overhead (counter + MAC + padding).
+ * and encryption overhead (counter + MAC + padding)
+ * and allow for a maximum of 1024 of compression expansion if
+ * enabled.
  */
-#define SSL_BUFFER_LEN (SSL_MAX_CONTENT_LEN + 512)
+#if defined(POLARSSL_ZLIB_SUPPORT)
+#define SSL_COMPRESSION_ADD          1024
+#else
+#define SSL_COMPRESSION_ADD             0
+#endif
+
+#define SSL_BUFFER_LEN (SSL_MAX_CONTENT_LEN + SSL_COMPRESSION_ADD + 512)
 
 /*
  * Supported ciphersuites
@@ -253,6 +267,7 @@ struct _ssl_session
 {
     time_t start;               /*!< starting time      */
     int ciphersuite;            /*!< chosen ciphersuite */
+    int compression;            /*!< chosen compression */
     size_t length;              /*!< session id length  */
     unsigned char id[32];       /*!< session identifier */
     unsigned char master[48];   /*!< the master secret  */
@@ -374,6 +389,11 @@ struct _ssl_context
     unsigned long ctx_enc[134];         /*!<  encryption context      */
     unsigned long ctx_dec[134];         /*!<  decryption context      */
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+    z_stream ctx_deflate;               /*!<  compression context     */
+    z_stream ctx_inflate;               /*!<  decompression context   */
+#endif
+
     /*
      * TLS extensions
      */
@@ -445,8 +465,10 @@ int ssl_init( ssl_context *ssl );
  *                 pointers and data.
  *
  * \param ssl      SSL context
+ * \return         0 if successful, or POLARSSL_ERR_SSL_HW_ACCEL_FAILED or
+ *                 POLARSSL_ERR_SSL_COMPRESSION_FAILED
  */
-void ssl_session_reset( ssl_context *ssl );
+int ssl_session_reset( ssl_context *ssl );
 
 /**
  * \brief          Set the current endpoint type
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 99120d569..49123795f 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -135,11 +135,21 @@ static int ssl_write_client_hello( ssl_context *ssl )
         *p++ = (unsigned char)( ssl->ciphersuites[i]      );
     }
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+    SSL_DEBUG_MSG( 3, ( "client hello, compress len.: %d", 2 ) );
+    SSL_DEBUG_MSG( 3, ( "client hello, compress alg.: %d %d",
+                        SSL_COMPRESS_NULL, SSL_COMPRESS_DEFLATE ) );
+
+    *p++ = 2;
+    *p++ = SSL_COMPRESS_NULL;
+    *p++ = SSL_COMPRESS_DEFLATE;
+#else
     SSL_DEBUG_MSG( 3, ( "client hello, compress len.: %d", 1 ) );
-    SSL_DEBUG_MSG( 3, ( "client hello, compress alg.: %d", 0 ) );
+    SSL_DEBUG_MSG( 3, ( "client hello, compress alg.: %d", SSL_COMPRESS_NULL ) );
 
     *p++ = 1;
     *p++ = SSL_COMPRESS_NULL;
+#endif
 
     if ( ssl->hostname != NULL )
     {
@@ -281,7 +291,7 @@ static int ssl_parse_server_hello( ssl_context *ssl )
 #if defined(POLARSSL_DEBUG_C)
     time_t t;
 #endif
-    int ret, i;
+    int ret, i, comp;
     size_t n;
     int ext_len;
     unsigned char *buf;
@@ -367,6 +377,7 @@ static int ssl_parse_server_hello( ssl_context *ssl )
     }
 
     i = ( buf[39 + n] << 8 ) | buf[40 + n];
+    comp = buf[41 + n];
 
     /*
      * Initialize update checksum functions
@@ -381,6 +392,7 @@ static int ssl_parse_server_hello( ssl_context *ssl )
      */
     if( ssl->resume == 0 || n == 0 ||
         ssl->session->ciphersuite != i ||
+        ssl->session->compression != comp ||
         ssl->session->length != n ||
         memcmp( ssl->session->id, buf + 39, n ) != 0 )
     {
@@ -388,6 +400,7 @@ static int ssl_parse_server_hello( ssl_context *ssl )
         ssl->resume = 0;
         ssl->session->start = time( NULL );
         ssl->session->ciphersuite = i;
+        ssl->session->compression = comp;
         ssl->session->length = n;
         memcpy( ssl->session->id, buf + 39, n );
     }
@@ -421,11 +434,16 @@ static int ssl_parse_server_hello( ssl_context *ssl )
             break;
     }
 
-    if( buf[41 + n] != SSL_COMPRESS_NULL )
+    if( comp != SSL_COMPRESS_NULL
+#if defined(POLARSSL_ZLIB_SUPPORT)
+        && comp != SSL_COMPRESS_DEFLATE
+#endif
+      )
     {
         SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
         return( POLARSSL_ERR_SSL_BAD_HS_SERVER_HELLO );
     }
+    ssl->session->compression = comp;
 
     /* TODO: Process extensions */
 
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index ecf153609..e4de68e8d 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -316,6 +316,18 @@ static int ssl_parse_client_hello( ssl_context *ssl )
             return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
         }
 
+        ssl->session->compression = SSL_COMPRESS_NULL;
+#if defined(POLARSSL_ZLIB_SUPPORT)
+        for( i = 0; i < comp_len; ++i )
+        {
+            if( buf[41 + sess_len + ciph_len + i] == SSL_COMPRESS_DEFLATE )
+            {
+                ssl->session->compression = SSL_COMPRESS_DEFLATE;
+                break;
+            }
+        }
+#endif
+
         SSL_DEBUG_BUF( 3, "client hello, random bytes",
                        buf +  6,  32 );
         SSL_DEBUG_BUF( 3, "client hello, session id",
@@ -449,11 +461,12 @@ static int ssl_write_server_hello( ssl_context *ssl )
 
     *p++ = (unsigned char)( ssl->session->ciphersuite >> 8 );
     *p++ = (unsigned char)( ssl->session->ciphersuite      );
-    *p++ = SSL_COMPRESS_NULL;
+    *p++ = (unsigned char)( ssl->session->compression      );
 
     SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %d",
                    ssl->session->ciphersuite ) );
-    SSL_DEBUG_MSG( 3, ( "server hello, compress alg.: %d", 0 ) );
+    SSL_DEBUG_MSG( 3, ( "server hello, compress alg.: %d",
+                   ssl->session->compression ) );
 
     ssl->out_msglen  = p - buf;
     ssl->out_msgtype = SSL_MSG_HANDSHAKE;
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index fab20046a..a458e6287 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -639,6 +639,25 @@ int ssl_derive_keys( ssl_context *ssl )
 
     memset( keyblk, 0, sizeof( keyblk ) );
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+    // Initialize compression
+    //
+    if( ssl->session->compression == SSL_COMPRESS_DEFLATE )
+    {
+        SSL_DEBUG_MSG( 3, ( "Initializing zlib states" ) );
+
+        memset( &ssl->ctx_deflate, 0, sizeof( ssl->ctx_deflate ) );
+        memset( &ssl->ctx_inflate, 0, sizeof( ssl->ctx_inflate ) );
+
+        if( deflateInit( &ssl->ctx_deflate, Z_DEFAULT_COMPRESSION ) != Z_OK ||
+            inflateInit( &ssl->ctx_inflate ) != Z_OK )
+        {
+            SSL_DEBUG_MSG( 1, ( "Failed to initialize compression" ) );
+            return( POLARSSL_ERR_SSL_COMPRESSION_FAILED );
+        }
+    }
+#endif /* POLARSSL_ZLIB_SUPPORT */
+
     SSL_DEBUG_MSG( 2, ( "<= derive keys" ) );
 
     return( 0 );
@@ -1397,6 +1416,113 @@ static int ssl_decrypt_buf( ssl_context *ssl )
     return( 0 );
 }
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+/*
+ * Compression/decompression functions
+ */
+static int ssl_compress_buf( ssl_context *ssl )
+{
+    int ret;
+    unsigned char *msg_post = ssl->out_msg;
+    size_t len_pre = ssl->out_msglen;
+    unsigned char *msg_pre;
+
+    SSL_DEBUG_MSG( 2, ( "=> compress buf" ) );
+
+    msg_pre = (unsigned char*) malloc( len_pre );
+    if( msg_pre == NULL )
+    {
+        SSL_DEBUG_MSG( 1, ( "malloc(%d bytes) failed", len_pre ) );
+        return( POLARSSL_ERR_SSL_MALLOC_FAILED );
+    }
+
+    memcpy( msg_pre, ssl->out_msg, len_pre );
+
+    SSL_DEBUG_MSG( 3, ( "before compression: msglen = %d, ",
+                   ssl->out_msglen ) );
+
+    SSL_DEBUG_BUF( 4, "before compression: output payload",
+                   ssl->out_msg, ssl->out_msglen );
+
+    ssl->ctx_deflate.next_in = msg_pre;
+    ssl->ctx_deflate.avail_in = len_pre;
+    ssl->ctx_deflate.next_out = msg_post;
+    ssl->ctx_deflate.avail_out = SSL_BUFFER_LEN;
+
+    ret = deflate( &ssl->ctx_deflate, Z_SYNC_FLUSH );
+    if( ret != Z_OK )
+    {
+        SSL_DEBUG_MSG( 1, ( "failed to perform compression (%d)", ret ) );
+        return( POLARSSL_ERR_SSL_COMPRESSION_FAILED );
+    }
+
+    ssl->out_msglen = SSL_BUFFER_LEN - ssl->ctx_deflate.avail_out;
+
+    free( msg_pre );
+
+    SSL_DEBUG_MSG( 3, ( "after compression: msglen = %d, ",
+                   ssl->out_msglen ) );
+
+    SSL_DEBUG_BUF( 4, "after compression: output payload",
+                   ssl->out_msg, ssl->out_msglen );
+
+    SSL_DEBUG_MSG( 2, ( "<= compress buf" ) );
+
+    return( 0 );
+}
+
+static int ssl_decompress_buf( ssl_context *ssl )
+{
+    int ret;
+    unsigned char *msg_post = ssl->in_msg;
+    size_t len_pre = ssl->in_msglen;
+    unsigned char *msg_pre;
+
+    SSL_DEBUG_MSG( 2, ( "=> decompress buf" ) );
+
+    msg_pre = (unsigned char*) malloc( len_pre );
+    if( msg_pre == NULL )
+    {
+        SSL_DEBUG_MSG( 1, ( "malloc(%d bytes) failed", len_pre ) );
+        return( POLARSSL_ERR_SSL_MALLOC_FAILED );
+    }
+
+    memcpy( msg_pre, ssl->in_msg, len_pre );
+
+    SSL_DEBUG_MSG( 3, ( "before decompression: msglen = %d, ",
+                   ssl->in_msglen ) );
+
+    SSL_DEBUG_BUF( 4, "before decompression: input payload",
+                   ssl->in_msg, ssl->in_msglen );
+
+    ssl->ctx_inflate.next_in = msg_pre;
+    ssl->ctx_inflate.avail_in = len_pre;
+    ssl->ctx_inflate.next_out = msg_post;
+    ssl->ctx_inflate.avail_out = SSL_MAX_CONTENT_LEN;
+
+    ret = inflate( &ssl->ctx_inflate, Z_SYNC_FLUSH );
+    if( ret != Z_OK )
+    {
+        SSL_DEBUG_MSG( 1, ( "failed to perform decompression (%d)", ret ) );
+        return( POLARSSL_ERR_SSL_COMPRESSION_FAILED );
+    }
+
+    ssl->in_msglen = SSL_MAX_CONTENT_LEN - ssl->ctx_inflate.avail_out;
+
+    free( msg_pre );
+
+    SSL_DEBUG_MSG( 3, ( "after decompression: msglen = %d, ",
+                   ssl->in_msglen ) );
+
+    SSL_DEBUG_BUF( 4, "after decompression: input payload",
+                   ssl->in_msg, ssl->in_msglen );
+
+    SSL_DEBUG_MSG( 2, ( "<= decompress buf" ) );
+
+    return( 0 );
+}
+#endif /* POLARSSL_ZLIB_SUPPORT */
+
 /*
  * Fill the input message buffer
  */
@@ -1495,6 +1621,20 @@ int ssl_write_record( ssl_context *ssl )
         ssl->update_checksum( ssl, ssl->out_msg, len );
     }
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+    if( ssl->do_crypt != 0 &&
+        ssl->session->compression == SSL_COMPRESS_DEFLATE )
+    {
+        if( ( ret = ssl_compress_buf( ssl ) ) != 0 )
+        {
+            SSL_DEBUG_RET( 1, "ssl_compress_buf", ret );
+            return( ret );
+        }
+
+        len = ssl->out_msglen;
+    }
+#endif /*POLARSSL_ZLIB_SUPPORT */
+
 #if defined(POLARSSL_SSL_HW_RECORD_ACCEL)
     if( ssl_hw_record_write != NULL)
     {
@@ -1708,6 +1848,21 @@ int ssl_read_record( ssl_context *ssl )
         }
     }
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+    if( ssl->do_crypt != 0 &&
+        ssl->session->compression == SSL_COMPRESS_DEFLATE )
+    {
+        if( ( ret = ssl_decompress_buf( ssl ) ) != 0 )
+        {
+            SSL_DEBUG_RET( 1, "ssl_decompress_buf", ret );
+            return( ret );
+        }
+
+        ssl->in_hdr[3] = (unsigned char)( ssl->in_msglen >> 8 );
+        ssl->in_hdr[4] = (unsigned char)( ssl->in_msglen      );
+    }
+#endif /* POLARSSL_ZLIB_SUPPORT */
+
     if( ssl->in_msgtype != SSL_MSG_HANDSHAKE &&
         ssl->in_msgtype != SSL_MSG_ALERT &&
         ssl->in_msgtype != SSL_MSG_CHANGE_CIPHER_SPEC &&
@@ -1761,12 +1916,13 @@ int ssl_read_record( ssl_context *ssl )
          */
         if( ssl->in_msg[0] == SSL_ALERT_LEVEL_FATAL )
         {
-            SSL_DEBUG_MSG( 1, ( "is a fatal alert message" ) );
+            SSL_DEBUG_MSG( 1, ( "is a fatal alert message (msg %d)",
+                           ssl->in_msg[1] ) );
             /**
              * Subtract from error code as ssl->in_msg[1] is 7-bit positive
              * error identifier.
              */
-            return( POLARSSL_ERR_SSL_FATAL_ALERT_MESSAGE - ssl->in_msg[1] );
+            return( POLARSSL_ERR_SSL_FATAL_ALERT_MESSAGE );
         }
 
         if( ssl->in_msg[0] == SSL_ALERT_LEVEL_WARNING &&
@@ -2514,7 +2670,7 @@ int ssl_init( ssl_context *ssl )
  * Reset an initialized and used SSL context for re-use while retaining
  * all application-set variables, function pointers and data.
  */
-void ssl_session_reset( ssl_context *ssl )
+int ssl_session_reset( ssl_context *ssl )
 {
     ssl->state = SSL_HELLO_REQUEST;
     
@@ -2555,9 +2711,39 @@ void ssl_session_reset( ssl_context *ssl )
     if( ssl_hw_record_reset != NULL)
     {
         SSL_DEBUG_MSG( 2, ( "going for ssl_hw_record_reset()" ) );
-        ssl_hw_record_reset( ssl );
+        if( ssl_hw_record_reset( ssl ) != 0 )
+        {
+            SSL_DEBUG_RET( 1, "ssl_hw_record_reset", ret );
+            return( POLARSSL_ERR_SSL_HW_ACCEL_FAILED );
+        }
     }
 #endif
+
+#if defined(POLARSSL_ZLIB_SUPPORT)
+    // Reset compression state
+    //
+    if( ssl->session->compression == SSL_COMPRESS_DEFLATE )
+    {
+        ssl->ctx_deflate.next_in = Z_NULL;
+        ssl->ctx_deflate.next_out = Z_NULL;
+        ssl->ctx_deflate.avail_in = 0;
+        ssl->ctx_deflate.avail_out = 0;
+
+        ssl->ctx_inflate.next_in = Z_NULL;
+        ssl->ctx_inflate.next_out = Z_NULL;
+        ssl->ctx_inflate.avail_in = 0;
+        ssl->ctx_inflate.avail_out = 0;
+
+        if( deflateReset( &ssl->ctx_deflate ) != Z_OK ||
+            inflateReset( &ssl->ctx_inflate ) != Z_OK )
+        {
+            SSL_DEBUG_MSG( 1, ( "Failed to reset compression" ) );
+            return( POLARSSL_ERR_SSL_COMPRESSION_FAILED );
+        }
+    }
+#endif /* POLARSSL_ZLIB_SUPPORT */
+
+    return( 0 );
 }
 
 /*
@@ -3265,6 +3451,11 @@ void ssl_free( ssl_context *ssl )
     }
 #endif
 
+#if defined(POLARSSL_ZLIB_SUPPORT)
+    deflateEnd( &ssl->ctx_deflate );
+    inflateEnd( &ssl->ctx_inflate );
+#endif
+
     SSL_DEBUG_MSG( 2, ( "<= free" ) );
 
     /* Actually free after last debug message */
diff --git a/programs/Makefile b/programs/Makefile
index d28bc53ce..3aab43c14 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -15,6 +15,11 @@ ifdef WINDOWS
 LDFLAGS += -lws2_32
 endif
 
+# Zlib shared library extensions:
+ifdef ZLIB
+LDFLAGS += -lz
+endif
+
 APPS =	aes/aescrypt2	aes/crypt_and_hash	\
 	hash/hello			hash/generic_sum	\
 	hash/md5sum			hash/sha1sum		\
diff --git a/programs/ssl/ssl_server.c b/programs/ssl/ssl_server.c
index 0d2478718..d38683425 100644
--- a/programs/ssl/ssl_server.c
+++ b/programs/ssl/ssl_server.c
@@ -151,7 +151,7 @@ int my_ciphersuites[] =
     0
 };
 
-#define DEBUG_LEVEL 0
+#define DEBUG_LEVEL 5
 
 void my_debug( void *ctx, int level, const char *str )
 {
diff --git a/tests/Makefile b/tests/Makefile
index fd5d6a53d..3ceb19f69 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -17,6 +17,11 @@ ifdef WINDOWS
 LDFLAGS += -lws2_32
 endif
 
+# Zlib shared library extensions:
+ifdef ZLIB
+LDFLAGS += -lz
+endif
+
 APPS =	test_suite_aes			test_suite_arc4			\
 		test_suite_base64		test_suite_camellia		\
 		test_suite_cipher.aes	test_suite_cipher.camellia	\