diff --git a/cproxy.c b/cproxy.c
index 934ce3dc..5f2f15fc 100644
--- a/cproxy.c
+++ b/cproxy.c
@@ -21,7 +21,7 @@ static void hmacmd5_chap(const unsigned char *challenge, int challen,
     void *hmacmd5_ctx;
     int pwlen;
 
-    hmacmd5_ctx = hmacmd5_make_context();
+    hmacmd5_ctx = hmacmd5_make_context(NULL);
 
     pwlen = strlen(passwd);
     if (pwlen>64) {
diff --git a/ssh.c b/ssh.c
index 957a378c..0b323d32 100644
--- a/ssh.c
+++ b/ssh.c
@@ -6565,6 +6565,17 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	    crStopV;
 	  matched:;
 	}
+
+        /* If the cipher over-rides the mac, then pick it */
+        if (s->cscipher_tobe && s->cscipher_tobe->required_mac) {
+            s->csmac_tobe = s->cscipher_tobe->required_mac;
+	    s->csmac_etm_tobe = !!(s->csmac_tobe->etm_name);
+        }
+        if (s->sccipher_tobe && s->sccipher_tobe->required_mac) {
+            s->scmac_tobe = s->sccipher_tobe->required_mac;
+	    s->scmac_etm_tobe = !!(s->scmac_tobe->etm_name);
+        }
+
 	if (s->pending_compression) {
 	    logevent("Server supports delayed compression; "
 		     "will try this later");
@@ -7078,7 +7089,7 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	ssh->csmac->free_context(ssh->cs_mac_ctx);
     ssh->csmac = s->csmac_tobe;
     ssh->csmac_etm = s->csmac_etm_tobe;
-    ssh->cs_mac_ctx = ssh->csmac->make_context();
+    ssh->cs_mac_ctx = ssh->csmac->make_context(ssh->cs_cipher_ctx);
 
     if (ssh->cs_comp_ctx)
 	ssh->cscomp->compress_cleanup(ssh->cs_comp_ctx);
@@ -7146,7 +7157,7 @@ static void do_ssh2_transport(Ssh ssh, const void *vin, int inlen,
 	ssh->scmac->free_context(ssh->sc_mac_ctx);
     ssh->scmac = s->scmac_tobe;
     ssh->scmac_etm = s->scmac_etm_tobe;
-    ssh->sc_mac_ctx = ssh->scmac->make_context();
+    ssh->sc_mac_ctx = ssh->scmac->make_context(ssh->sc_cipher_ctx);
 
     if (ssh->sc_comp_ctx)
 	ssh->sccomp->decompress_cleanup(ssh->sc_comp_ctx);
diff --git a/ssh.h b/ssh.h
index 81c003ba..0bcf2b67 100644
--- a/ssh.h
+++ b/ssh.h
@@ -250,7 +250,7 @@ void MD5Update(struct MD5Context *context, unsigned char const *buf,
 void MD5Final(unsigned char digest[16], struct MD5Context *context);
 void MD5Simple(void const *p, unsigned len, unsigned char output[16]);
 
-void *hmacmd5_make_context(void);
+void *hmacmd5_make_context(void *);
 void hmacmd5_free_context(void *handle);
 void hmacmd5_key(void *handle, void const *key, int len);
 void hmacmd5_do_hmac(void *handle, unsigned char const *blk, int len,
@@ -296,6 +296,7 @@ void SHA384_Init(SHA384_State * s);
 void SHA384_Final(SHA384_State * s, unsigned char *output);
 void SHA384_Simple(const void *p, int len, unsigned char *output);
 
+struct ssh_mac;
 struct ssh_cipher {
     void *(*make_context)(void);
     void (*free_context)(void *);
@@ -319,6 +320,8 @@ struct ssh2_cipher {
     unsigned int flags;
 #define SSH_CIPHER_IS_CBC	1
     const char *text_name;
+    /* If set, this takes priority over other MAC. */
+    const struct ssh_mac *required_mac;
 };
 
 struct ssh2_ciphers {
@@ -327,7 +330,8 @@ struct ssh2_ciphers {
 };
 
 struct ssh_mac {
-    void *(*make_context)(void);
+    /* Passes in the cipher context */
+    void *(*make_context)(void *);
     void (*free_context)(void *);
     void (*setkey) (void *, unsigned char *key);
     /* whole-packet operations */
diff --git a/sshaes.c b/sshaes.c
index 97935b7f..83cc1bb3 100644
--- a/sshaes.c
+++ b/sshaes.c
@@ -1173,49 +1173,56 @@ static const struct ssh2_cipher ssh_aes128_ctr = {
     aes_make_context, aes_free_context, aes_iv, aes128_key,
     aes_ssh2_sdctr, aes_ssh2_sdctr,
     "aes128-ctr",
-    16, 128, 0, "AES-128 SDCTR"
+    16, 128, 0, "AES-128 SDCTR",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_aes192_ctr = {
     aes_make_context, aes_free_context, aes_iv, aes192_key,
     aes_ssh2_sdctr, aes_ssh2_sdctr,
     "aes192-ctr",
-    16, 192, 0, "AES-192 SDCTR"
+    16, 192, 0, "AES-192 SDCTR",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_aes256_ctr = {
     aes_make_context, aes_free_context, aes_iv, aes256_key,
     aes_ssh2_sdctr, aes_ssh2_sdctr,
     "aes256-ctr",
-    16, 256, 0, "AES-256 SDCTR"
+    16, 256, 0, "AES-256 SDCTR",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_aes128 = {
     aes_make_context, aes_free_context, aes_iv, aes128_key,
     aes_ssh2_encrypt_blk, aes_ssh2_decrypt_blk,
     "aes128-cbc",
-    16, 128, SSH_CIPHER_IS_CBC, "AES-128 CBC"
+    16, 128, SSH_CIPHER_IS_CBC, "AES-128 CBC",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_aes192 = {
     aes_make_context, aes_free_context, aes_iv, aes192_key,
     aes_ssh2_encrypt_blk, aes_ssh2_decrypt_blk,
     "aes192-cbc",
-    16, 192, SSH_CIPHER_IS_CBC, "AES-192 CBC"
+    16, 192, SSH_CIPHER_IS_CBC, "AES-192 CBC",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_aes256 = {
     aes_make_context, aes_free_context, aes_iv, aes256_key,
     aes_ssh2_encrypt_blk, aes_ssh2_decrypt_blk,
     "aes256-cbc",
-    16, 256, SSH_CIPHER_IS_CBC, "AES-256 CBC"
+    16, 256, SSH_CIPHER_IS_CBC, "AES-256 CBC",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_rijndael_lysator = {
     aes_make_context, aes_free_context, aes_iv, aes256_key,
     aes_ssh2_encrypt_blk, aes_ssh2_decrypt_blk,
     "rijndael-cbc@lysator.liu.se",
-    16, 256, SSH_CIPHER_IS_CBC, "AES-256 CBC"
+    16, 256, SSH_CIPHER_IS_CBC, "AES-256 CBC",
+    NULL
 };
 
 static const struct ssh2_cipher *const aes_list[] = {
diff --git a/ssharcf.c b/ssharcf.c
index 06f235c5..cec65c11 100644
--- a/ssharcf.c
+++ b/ssharcf.c
@@ -102,14 +102,16 @@ const struct ssh2_cipher ssh_arcfour128_ssh2 = {
     arcfour_make_context, arcfour_free_context, arcfour_iv, arcfour128_key,
     arcfour_block, arcfour_block,
     "arcfour128",
-    1, 128, 0, "Arcfour-128"
+    1, 128, 0, "Arcfour-128",
+    NULL
 };
 
 const struct ssh2_cipher ssh_arcfour256_ssh2 = {
     arcfour_make_context, arcfour_free_context, arcfour_iv, arcfour256_key,
     arcfour_block, arcfour_block,
     "arcfour256",
-    1, 256, 0, "Arcfour-256"
+    1, 256, 0, "Arcfour-256",
+    NULL
 };
 
 static const struct ssh2_cipher *const arcfour_list[] = {
diff --git a/sshblowf.c b/sshblowf.c
index 70709f64..bf0b1641 100644
--- a/sshblowf.c
+++ b/sshblowf.c
@@ -643,14 +643,16 @@ static const struct ssh2_cipher ssh_blowfish_ssh2 = {
     blowfish_make_context, blowfish_free_context, blowfish_iv, blowfish_key,
     blowfish_ssh2_encrypt_blk, blowfish_ssh2_decrypt_blk,
     "blowfish-cbc",
-    8, 128, SSH_CIPHER_IS_CBC, "Blowfish-128 CBC"
+    8, 128, SSH_CIPHER_IS_CBC, "Blowfish-128 CBC",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_blowfish_ssh2_ctr = {
     blowfish_make_context, blowfish_free_context, blowfish_iv, blowfish256_key,
     blowfish_ssh2_sdctr, blowfish_ssh2_sdctr,
     "blowfish-ctr",
-    8, 256, 0, "Blowfish-256 SDCTR"
+    8, 256, 0, "Blowfish-256 SDCTR",
+    NULL
 };
 
 static const struct ssh2_cipher *const blowfish_list[] = {
diff --git a/sshdes.c b/sshdes.c
index f54990e7..2f3e3c7a 100644
--- a/sshdes.c
+++ b/sshdes.c
@@ -949,14 +949,16 @@ static const struct ssh2_cipher ssh_3des_ssh2 = {
     des3_make_context, des3_free_context, des3_iv, des3_key,
     des3_ssh2_encrypt_blk, des3_ssh2_decrypt_blk,
     "3des-cbc",
-    8, 168, SSH_CIPHER_IS_CBC, "triple-DES CBC"
+    8, 168, SSH_CIPHER_IS_CBC, "triple-DES CBC",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_3des_ssh2_ctr = {
     des3_make_context, des3_free_context, des3_iv, des3_key,
     des3_ssh2_sdctr, des3_ssh2_sdctr,
     "3des-ctr",
-    8, 168, 0, "triple-DES SDCTR"
+    8, 168, 0, "triple-DES SDCTR",
+    NULL
 };
 
 /*
@@ -971,14 +973,16 @@ static const struct ssh2_cipher ssh_des_ssh2 = {
     des_make_context, des3_free_context, des3_iv, des_key,
     des_ssh2_encrypt_blk, des_ssh2_decrypt_blk,
     "des-cbc",
-    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC"
+    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC",
+    NULL
 };
 
 static const struct ssh2_cipher ssh_des_sshcom_ssh2 = {
     des_make_context, des3_free_context, des3_iv, des_key,
     des_ssh2_encrypt_blk, des_ssh2_decrypt_blk,
     "des-cbc@ssh.com",
-    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC"
+    8, 56, SSH_CIPHER_IS_CBC, "single-DES CBC",
+    NULL
 };
 
 static const struct ssh2_cipher *const des3_list[] = {
diff --git a/sshmd5.c b/sshmd5.c
index f34f851d..4988223e 100644
--- a/sshmd5.c
+++ b/sshmd5.c
@@ -221,7 +221,7 @@ void MD5Simple(void const *p, unsigned len, unsigned char output[16])
  * useful elsewhere (SOCKS5 CHAP authentication uses HMAC-MD5).
  */
 
-void *hmacmd5_make_context(void)
+void *hmacmd5_make_context(void *cipher_ctx)
 {
     return snewn(3, struct MD5Context);
 }
diff --git a/sshsh256.c b/sshsh256.c
index b583c9b3..8e3d4fc1 100644
--- a/sshsh256.c
+++ b/sshsh256.c
@@ -225,7 +225,7 @@ const struct ssh_hash ssh_sha256 = {
  * HMAC wrapper on it.
  */
 
-static void *sha256_make_context(void)
+static void *sha256_make_context(void *cipher_ctx)
 {
     return snewn(3, SHA256_State);
 }
diff --git a/sshsha.c b/sshsha.c
index 4d24e7b2..2b2eead1 100644
--- a/sshsha.c
+++ b/sshsha.c
@@ -255,7 +255,7 @@ const struct ssh_hash ssh_sha1 = {
  * HMAC wrapper on it.
  */
 
-static void *sha1_make_context(void)
+static void *sha1_make_context(void *cipher_ctx)
 {
     return snewn(3, SHA_State);
 }