diff --git a/dev-libs/boost/patches/boost-1.65.1.patchset b/dev-libs/boost/patches/boost-1.65.1.patchset
index 5838012f4..446186cf1 100644
--- a/dev-libs/boost/patches/boost-1.65.1.patchset
+++ b/dev-libs/boost/patches/boost-1.65.1.patchset
@@ -172,7 +172,7 @@ index e711c08..f81e349 100644
  }
 +if $(OS) = HAIKU
 +{
-+	--defs += _BSDSOURCE ;
++	--defs += _BSD_SOURCE ;
 +	--libs += -lbsd ;
 +}
  --defs += YYSTACKSIZE=5000 ;