diff --git a/lib/msun/Makefile b/lib/msun/Makefile
index 4c24e686f5d4..03d153d2ee63 100644
--- a/lib/msun/Makefile
+++ b/lib/msun/Makefile
@@ -26,8 +26,6 @@ ARCH_SUBDIR= ${MACHINE_ARCH}
 .PATH:	${.CURDIR}/man
 .PATH:	${.CURDIR}/src
 
-CFLAGS+= -D_IEEE_LIBM
-
 LIB=	m
 SHLIBDIR?= /lib
 SHLIB_MAJOR= 3