Add cast to satisfy gcc -Wsign-compare
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 65b4739..8c29f1d 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -581,7 +581,7 @@
         goto destroy;
 
  
-    TEST_ASSERT( exported_length == public_key_expected_length );
+    TEST_ASSERT( exported_length == (size_t) public_key_expected_length );
 
 destroy:
     /* Destroy the key */