diff --git a/library/constant_time.c b/library/constant_time.c
index c3f0773..fa1060d 100644
--- a/library/constant_time.c
+++ b/library/constant_time.c
@@ -550,6 +550,7 @@
     mbedtls_platform_zeroize( mac_key, MBEDTLS_MD_MAX_BLOCK_SIZE );
     mbedtls_platform_zeroize( ikey, MBEDTLS_MD_MAX_BLOCK_SIZE );
     mbedtls_platform_zeroize( okey, MBEDTLS_MD_MAX_BLOCK_SIZE );
+    mbedtls_platform_zeroize( aux_out, MBEDTLS_MD_MAX_SIZE );
     psa_hash_abort( &operation );
     psa_hash_abort( &aux_operation );
     return( status == PSA_SUCCESS ? 0 : MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED );