diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index f137c3d..97d7a9e 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -3436,7 +3436,7 @@
     /*
      * Receive client pre-shared key identity name
      */
-    if( *p + 2 > end )
+    if( end - *p < 2 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
@@ -3445,7 +3445,7 @@
     n = ( (*p)[0] << 8 ) | (*p)[1];
     *p += 2;
 
-    if( n < 1 || n > 65535 || *p + n > end )
+    if( n < 1 || n > 65535 || n > (size_t) ( end - *p ) )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );