diff --git a/lib/libc/gen/isnan.c b/lib/libc/gen/isnan.c
index 52cec1bb7405..ec81362f4f99 100644
--- a/lib/libc/gen/isnan.c
+++ b/lib/libc/gen/isnan.c
@@ -55,13 +55,3 @@ __isnanf(float f)
 	u.f = f;
 	return (u.bits.exp == 255 && u.bits.man != 0);
 }
-
-int
-__isnanl(long double e)
-{
-	union IEEEl2bits u;
-
-	u.e = e;
-	mask_nbit_l(u);
-	return (u.bits.exp == 32767 && (u.bits.manl != 0 || u.bits.manh != 0));
-}