diff --git a/libs/pbd/tlsf.cc b/libs/pbd/tlsf.cc
index 0bc9c9dd34..bdfdf6cb58 100644
--- a/libs/pbd/tlsf.cc
+++ b/libs/pbd/tlsf.cc
@@ -304,14 +304,14 @@ static __inline__ void MAPPING_INSERT(size_t _r, int *_fl, int *_sl)
 
 static __inline__ bhdr_t *FIND_SUITABLE_BLOCK(tlsf_t * _tlsf, int *_fl, int *_sl)
 {
-	u32_t _tmp = _tlsf->sl_bitmap[*_fl] & (~u32_t(0) << *_sl);
+	u32_t _tmp = _tlsf->sl_bitmap[*_fl] & (~((u32_t)0) << *_sl);
 	bhdr_t *_b = NULL;
 
 	if (_tmp) {
 		*_sl = ls_bit(_tmp);
 		_b = _tlsf->matrix[*_fl][*_sl];
 	} else {
-		*_fl = ls_bit(_tlsf->fl_bitmap & (~u32_t(0) << (*_fl + 1)));
+		*_fl = ls_bit(_tlsf->fl_bitmap & (~((u32_t)0) << (*_fl + 1)));
 		if (*_fl > 0) {         /* likely */
 			*_sl = ls_bit(_tlsf->sl_bitmap[*_fl]);
 			_b = _tlsf->matrix[*_fl][*_sl];