diff --git a/library/pkcs12.c b/library/pkcs12.c
index 4bdeb68..9823d96 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -60,21 +60,21 @@
      *
      */
     if( params->tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &salt->len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT, ret ) );
 
     salt->p = *p;
     *p += salt->len;
 
     if( ( ret = mbedtls_asn1_get_int( p, end, iterations ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT, ret ) );
 
     if( *p != end )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }