diff --git a/library/x509write_csr.c b/library/x509write_csr.c
index a58374f..591fb6d 100644
--- a/library/x509write_csr.c
+++ b/library/x509write_csr.c
@@ -222,7 +222,7 @@
                           c,
                           len,
                           hash,
-                          PSA_HASH_MAX_SIZE,
+                          sizeof( hash ),
                           &hash_len ) != PSA_SUCCESS )
     {
         return ( MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED );