diff --git a/include/polarssl/cipher.h b/include/polarssl/cipher.h
index cc69208..aad488f 100644
--- a/include/polarssl/cipher.h
+++ b/include/polarssl/cipher.h
@@ -512,6 +512,10 @@
  *                      POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE on an
  *                      unsupported mode for a cipher or a cipher specific
  *                      error code.
+ *
+ * \note                If the underlying cipher is GCM, all calls to this
+ *                      function, except the last one before cipher_finish(),
+ *                      must have ilen a multiple of the block size.
  */
 int cipher_update( cipher_context_t *ctx, const unsigned char *input, size_t ilen,
         unsigned char *output, size_t *olen );
diff --git a/library/cipher.c b/library/cipher.c
index 280124d..8d90a64 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -467,14 +467,21 @@
         return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
     }
 
+#if defined(POLARSSL_GCM_C)
+    if( ctx->cipher_info->mode == POLARSSL_MODE_GCM)
+    {
+        *olen = ilen;
+        return gcm_update( ctx->cipher_ctx, ilen, input, output );
+    }
+#endif
+
     if( input == output &&
        ( ctx->unprocessed_len != 0 || ilen % cipher_get_block_size( ctx ) ) )
     {
         return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
     }
 
-    if( ctx->cipher_info->mode == POLARSSL_MODE_CBC ||
-        ctx->cipher_info->mode == POLARSSL_MODE_GCM )
+    if( ctx->cipher_info->mode == POLARSSL_MODE_CBC )
     {
         /*
          * If there is not enough data for a full block, cache it.
@@ -501,18 +508,6 @@
             memcpy( &( ctx->unprocessed_data[ctx->unprocessed_len] ), input,
                     copy_len );
 
-#if defined(POLARSSL_GCM_C)
-            if( ctx->cipher_info->mode == POLARSSL_MODE_GCM )
-            {
-                if( 0 != ( ret = gcm_update( ctx->cipher_ctx,
-                                cipher_get_block_size( ctx ),
-                                ctx->unprocessed_data, output ) ) )
-                {
-                    return ret;
-                }
-            }
-            else
-#endif
             if( 0 != ( ret = ctx->cipher_info->base->cbc_func( ctx->cipher_ctx,
                     ctx->operation, cipher_get_block_size( ctx ), ctx->iv,
                     ctx->unprocessed_data, output ) ) )
@@ -549,17 +544,6 @@
          */
         if( ilen )
         {
-#if defined(POLARSSL_GCM_C)
-            if( ctx->cipher_info->mode == POLARSSL_MODE_GCM )
-            {
-                if( 0 != ( ret = gcm_update( ctx->cipher_ctx,
-                                             ilen, input, output ) ) )
-                {
-                    return ret;
-                }
-            }
-            else
-#endif
             if( 0 != ( ret = ctx->cipher_info->base->cbc_func( ctx->cipher_ctx,
                     ctx->operation, ilen, ctx->iv, input, output ) ) )
             {
@@ -790,27 +774,12 @@
 
     if( POLARSSL_MODE_CFB == ctx->cipher_info->mode ||
         POLARSSL_MODE_CTR == ctx->cipher_info->mode ||
+        POLARSSL_MODE_GCM == ctx->cipher_info->mode ||
         POLARSSL_MODE_STREAM == ctx->cipher_info->mode )
     {
         return 0;
     }
 
-#if defined(POLARSSL_GCM_C)
-    if( POLARSSL_MODE_GCM == ctx->cipher_info->mode )
-    {
-        if( 0 != ( ret = gcm_update( ctx->cipher_ctx,
-                        ctx->unprocessed_len, ctx->unprocessed_data,
-                        output ) ) )
-        {
-            return( ret );
-        }
-
-        *olen += ctx->unprocessed_len;
-
-        return( 0 );
-    }
-#endif
-
     if( POLARSSL_MODE_CBC == ctx->cipher_info->mode )
     {
         if( POLARSSL_ENCRYPT == ctx->operation )
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index cddaec6..7e7ddd7 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -690,16 +690,6 @@
             }
             break;
 
-#if defined(POLARSSL_GCM_C)
-        case POLARSSL_CIPHER_AES_128_GCM:
-        case POLARSSL_CIPHER_AES_256_GCM:
-            gcm_init( (gcm_context *) transform->ctx_enc, key1,
-                      cipher_info->key_length );
-            gcm_init( (gcm_context *) transform->ctx_dec, key2,
-                      cipher_info->key_length );
-            break;
-#endif
-
         case POLARSSL_CIPHER_NULL:
             break;
 
@@ -1046,7 +1036,7 @@
          */
         ssl->out_msglen += 16;
 
-        gcm_crypt_and_tag( ssl->transform_out->cipher_ctx_enc->cipher_ctx,
+        gcm_crypt_and_tag( ssl->transform_out->cipher_ctx_enc.cipher_ctx,
                 GCM_ENCRYPT, enc_msglen,
                 ssl->transform_out->iv_enc, ssl->transform_out->ivlen,
                 add_data, 13,
@@ -1285,7 +1275,7 @@
                                      ssl->transform_in->ivlen );
         SSL_DEBUG_BUF( 4, "TAG used", dec_msg + dec_msglen, 16 );
 
-        ret = gcm_auth_decrypt(  ssl->transform_in->cipher_ctx_dec->cipher_ctx,
+        ret = gcm_auth_decrypt(  ssl->transform_in->cipher_ctx_dec.cipher_ctx,
                                  dec_msglen,
                                  ssl->transform_in->iv_dec,
                                  ssl->transform_in->ivlen,
diff --git a/tests/suites/test_suite_cipher.gcm.data b/tests/suites/test_suite_cipher.gcm.data
index 7a83dc5..7681d18 100644
--- a/tests/suites/test_suite_cipher.gcm.data
+++ b/tests/suites/test_suite_cipher.gcm.data
@@ -85,25 +85,13 @@
 depends_on:POLARSSL_AES_C:POLARSSL_GCM_C
 enc_dec_buf_multipart:POLARSSL_CIPHER_AES_128_GCM:128:0:16
 
-AES 128 GCM Encrypt and decrypt 16 bytes in multiple parts 3
-depends_on:POLARSSL_AES_C:POLARSSL_GCM_C
-enc_dec_buf_multipart:POLARSSL_CIPHER_AES_128_GCM:128:1:15
-
-AES 128 GCM Encrypt and decrypt 16 bytes in multiple parts 4
-depends_on:POLARSSL_AES_C:POLARSSL_GCM_C
-enc_dec_buf_multipart:POLARSSL_CIPHER_AES_128_GCM:128:15:1
-
-AES 128 GCM Encrypt and decrypt 22 bytes in multiple parts 1
-depends_on:POLARSSL_AES_C:POLARSSL_GCM_C
-enc_dec_buf_multipart:POLARSSL_CIPHER_AES_128_GCM:128:15:7
-
 AES 128 GCM Encrypt and decrypt 22 bytes in multiple parts 1
 depends_on:POLARSSL_AES_C:POLARSSL_GCM_C
 enc_dec_buf_multipart:POLARSSL_CIPHER_AES_128_GCM:128:16:6
 
-AES 128 GCM Encrypt and decrypt 22 bytes in multiple parts 1
+AES 128 GCM Encrypt and decrypt 22 bytes in multiple parts 2
 depends_on:POLARSSL_AES_C:POLARSSL_GCM_C
-enc_dec_buf_multipart:POLARSSL_CIPHER_AES_128_GCM:128:17:6
+enc_dec_buf_multipart:POLARSSL_CIPHER_AES_128_GCM:128:0:22
 
 AES 128 GCM Encrypt and decrypt 32 bytes in multiple parts 1
 depends_on:POLARSSL_AES_C:POLARSSL_GCM_C