diff --git a/tests/src/psa_exercise_key.c b/tests/src/psa_exercise_key.c
index 479d91d..9f80d7b 100644
--- a/tests/src/psa_exercise_key.c
+++ b/tests/src/psa_exercise_key.c
@@ -46,7 +46,7 @@
     psa_key_lifetime_t lifetime;
     mbedtls_svc_key_id_t id;
     psa_key_type_t type;
-    psa_key_type_t bits;
+    size_t bits;
 
     PSA_ASSERT( psa_get_key_attributes( key, &attributes ) );
     lifetime = psa_get_key_lifetime( &attributes );