diff --git a/lib/msun/tests/Makefile b/lib/msun/tests/Makefile
index dde46be8a394..0479cfb63801 100644
--- a/lib/msun/tests/Makefile
+++ b/lib/msun/tests/Makefile
@@ -9,7 +9,9 @@ TESTSDIR=	${TESTSBASE}/lib/msun
 # All architectures on FreeBSD have fenv.h
 CFLAGS+=	-DHAVE_FENV_H
 
-.if ${MACHINE} == "amd64" || ${MACHINE} == "i386"
+# Not sure why this isn't defined for all architectures, since most
+# have long double.
+.if ${MACHINE_CPUARCH} == "amd64" || ${MACHINE_CPUARCH} == "i386"
 CFLAGS+=	-D__HAVE_LONG_DOUBLE
 .endif