diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index 5fa8a69..6b695cb 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -423,6 +423,9 @@
     mbedtls_pk_context pk;
     size_t hash_len = (size_t)-1;
 
+    if( sizeof( size_t ) <= sizeof( unsigned int ) )
+        return;
+
     mbedtls_pk_init( &pk );
 
     TEST_ASSERT( mbedtls_pk_setup( &pk,
@@ -493,9 +496,12 @@
     TEST_ASSERT( mbedtls_pk_sign( &alt, MBEDTLS_MD_NONE, hash, sizeof hash,
                           sig, &sig_len, rnd_std_rand, NULL ) == 0 );
 #if defined(MBEDTLS_HAVE_INT64)
-    TEST_ASSERT( mbedtls_pk_sign( &alt, MBEDTLS_MD_NONE, hash, (size_t)-1,
-                          NULL, NULL, rnd_std_rand, NULL ) ==
-                 MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+    if( sizeof( size_t ) > sizeof( unsigned int ) )
+    {
+        TEST_ASSERT( mbedtls_pk_sign( &alt, MBEDTLS_MD_NONE, hash, (size_t)-1,
+                              NULL, NULL, rnd_std_rand, NULL ) ==
+                     MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+    }
 #endif /* MBEDTLS_HAVE_INT64 */
     TEST_ASSERT( sig_len == RSA_KEY_LEN );
     TEST_ASSERT( mbedtls_pk_verify( &rsa, MBEDTLS_MD_NONE,