diff --git a/ChangeLog b/ChangeLog
index 4d6b7de..dd1a3c5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,10 @@
      (server is not affected if it doesn't ask for a client certificate).
      (Found using Codenomicon Defensics.)
 
+Bugfix
+   * Fix potential bad read in parsing ServerHello (found by Adrien
+     Vialletelle).
+
 Changes
    * X.509 certificates with more than one AttributeTypeAndValue per
      RelativeDistinguishedName are not accepted any more.
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 15fc554..032e506 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -377,7 +377,7 @@
 #endif
     int ret, i, comp;
     size_t n;
-    size_t ext_len = 0;
+    size_t ext_len;
     unsigned char *buf, *ext;
     int renegotiation_info_seen = 0;
     int handshake_failure = 0;
@@ -464,7 +464,7 @@
      *   42+n . 43+n  extensions length
      *   44+n . 44+n+m extensions
      */
-    if( ssl->in_hslen > 42 + n )
+    if( ssl->in_hslen > 43 + n )
     {
         ext_len = ( ( buf[42 + n] <<  8 )
                   | ( buf[43 + n]       ) );
@@ -476,6 +476,15 @@
             return( POLARSSL_ERR_SSL_BAD_HS_SERVER_HELLO );
         }
     }
+    else if( ssl->in_hslen == 42 + n )
+    {
+        ext_len = 0;
+    }
+    else
+    {
+        SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        return( POLARSSL_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
 
     i = ( buf[39 + n] << 8 ) | buf[40 + n];
     comp = buf[41 + n];