diff --git a/library/pk.c b/library/pk.c
index 513d8cadd..a37f58e12 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -306,18 +306,24 @@ int pk_encrypt( pk_context *ctx,
 int pk_check_pair( const pk_context *pub, const pk_context *prv )
 {
     if( pub == NULL || pub->pk_info == NULL ||
-        prv == NULL || prv->pk_info == NULL )
+        prv == NULL || prv->pk_info == NULL ||
+        prv->pk_info->check_pair_func == NULL )
     {
         return( POLARSSL_ERR_PK_BAD_INPUT_DATA );
     }
 
-    if( pub->pk_info != prv->pk_info ||
-        pub->pk_info->check_pair_func == NULL )
+    if( prv->pk_info->type == POLARSSL_PK_RSA_ALT )
     {
-        return( POLARSSL_ERR_PK_TYPE_MISMATCH );
+        if( pub->pk_info->type != POLARSSL_PK_RSA )
+            return( POLARSSL_ERR_PK_TYPE_MISMATCH );
+    }
+    else
+    {
+        if( pub->pk_info != prv->pk_info )
+            return( POLARSSL_ERR_PK_TYPE_MISMATCH );
     }
 
-    return( pub->pk_info->check_pair_func( pub->pk_ctx, prv->pk_ctx ) );
+    return( prv->pk_info->check_pair_func( pub->pk_ctx, prv->pk_ctx ) );
 }
 
 /*
diff --git a/library/pk_wrap.c b/library/pk_wrap.c
index 0d2a368ad..a75ab3248 100644
--- a/library/pk_wrap.c
+++ b/library/pk_wrap.c
@@ -117,10 +117,11 @@ static int rsa_encrypt_wrap( void *ctx,
                     unsigned char *output, size_t *olen, size_t osize,
                     int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
-    ((void) osize);
-
     *olen = ((rsa_context *) ctx)->len;
 
+    if( *olen > osize )
+        return( POLARSSL_ERR_RSA_OUTPUT_TOO_LARGE );
+
     return( rsa_pkcs1_encrypt( (rsa_context *) ctx,
                 f_rng, p_rng, RSA_PUBLIC, ilen, input, output ) );
 }
@@ -435,6 +436,34 @@ static int rsa_alt_decrypt_wrap( void *ctx,
                 RSA_PRIVATE, olen, input, output, osize ) );
 }
 
+static int rsa_alt_check_pair( const void *pub, const void *prv )
+{
+    unsigned char sig[POLARSSL_MPI_MAX_SIZE];
+    unsigned char hash[32];
+    size_t sig_len = 0;
+    int ret;
+
+    if( rsa_alt_get_size( prv ) != rsa_get_size( pub ) )
+        return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
+
+    memset( hash, 0x2a, sizeof( hash ) );
+
+    if( ( ret = rsa_alt_sign_wrap( (void *) prv, POLARSSL_MD_NONE,
+                                   hash, sizeof( hash ),
+                                   sig, &sig_len, NULL, NULL ) ) != 0 )
+    {
+        return( ret );
+    }
+
+    if( rsa_verify_wrap( (void *) pub, POLARSSL_MD_NONE,
+                         hash, sizeof( hash ), sig, sig_len ) != 0 )
+    {
+        return( POLARSSL_ERR_RSA_KEY_CHECK_FAILED );
+    }
+
+    return( 0 );
+}
+
 static void *rsa_alt_alloc_wrap( void )
 {
     void *ctx = polarssl_malloc( sizeof( rsa_alt_context ) );
@@ -460,7 +489,7 @@ const pk_info_t rsa_alt_info = {
     rsa_alt_sign_wrap,
     rsa_alt_decrypt_wrap,
     NULL,
-    NULL,                   /* No public key */
+    rsa_alt_check_pair,
     rsa_alt_alloc_wrap,
     rsa_alt_free_wrap,
     NULL,
diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index 352169c24..c88d36588 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -83,18 +83,27 @@ exit:
 /* BEGIN_CASE depends_on:POLARSSL_PK_PARSE_C */
 void pk_check_pair( char *pub_file, char *prv_file, int ret )
 {
-    pk_context pub, prv;
+    pk_context pub, prv, alt;
 
     pk_init( &pub );
     pk_init( &prv );
+    pk_init( &alt );
 
     TEST_ASSERT( pk_parse_public_keyfile( &pub, pub_file ) == 0 );
     TEST_ASSERT( pk_parse_keyfile( &prv, prv_file, NULL ) == 0 );
 
     TEST_ASSERT( pk_check_pair( &pub, &prv ) == ret );
 
+    if( pk_get_type( &prv ) == POLARSSL_PK_RSA )
+    {
+        TEST_ASSERT( pk_init_ctx_rsa_alt( &alt, pk_rsa( prv ),
+                     rsa_decrypt_func, rsa_sign_func, rsa_key_len_func ) == 0 );
+        TEST_ASSERT( pk_check_pair( &pub, &alt ) == ret );
+    }
+
     pk_free( &pub );
     pk_free( &prv );
+    pk_free( &alt );
 }
 /* END_CASE */