diff --git a/liba/Makefile b/liba/Makefile
index 31de8ce6f..e3659c1a2 100644
--- a/liba/Makefile
+++ b/liba/Makefile
@@ -65,6 +65,7 @@ liba_src += $(addprefix liba/src/external/openbsd/, \
   s_frexp.c \
   s_log1pf.c \
   s_logb.c \
+  s_logbf.c \
   s_modf.c \
   s_modff.c \
   s_rint.c \
diff --git a/liba/src/external/openbsd/s_logbf.c b/liba/src/external/openbsd/s_logbf.c
new file mode 100644
index 000000000..f8b1e25f3
--- /dev/null
+++ b/liba/src/external/openbsd/s_logbf.c
@@ -0,0 +1,42 @@
+/* s_logbf.c -- float version of s_logb.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ * Taken from openlibm at 5b0e7e981321687ac0abe711fdeb30adcd9da932 and
+ * modified for Numworks Epsilon by Neven Sajko <nsajko@gmail.com>
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+//__FBSDID("$FreeBSD: src/lib/msun/src/s_logbf.c,v 1.9 2008/02/22 02:30:35 das Exp $");
+
+#include "math.h"
+
+#include "math_private.h"
+
+static const float
+two25 = 3.355443200e+07;		/* 0x4c000000 */
+
+float
+logbf(float x)
+{
+	int32_t ix;
+	GET_FLOAT_WORD(ix,x);
+	ix &= 0x7fffffff;			/* high |x| */
+	if(ix==0) return (float)-1.0/fabsf(x);
+	if(ix>=0x7f800000) return x*x;
+	if(ix<0x00800000) {
+		x *= two25;		 /* convert subnormal x to normal */
+		GET_FLOAT_WORD(ix,x);
+		ix &= 0x7fffffff;
+		return (float) ((ix>>23)-127-25);
+	} else
+		return (float) ((ix>>23)-127);
+}
diff --git a/libaxx/include/cmath b/libaxx/include/cmath
index 6a3e3894e..5bcfbfa7b 100644
--- a/libaxx/include/cmath
+++ b/libaxx/include/cmath
@@ -121,12 +121,14 @@ inline constexpr float floor(float x) { return __builtin_floorf(x); }
 inline constexpr float fmax(float x, float y) { return __builtin_fmaxf(x, y); }
 inline constexpr float fmod(float x, float y) { return __builtin_fmodf(x, y); }
 inline constexpr float frexp(float x, int *exp) { return __builtin_frexpf(x, exp); }
+inline constexpr float hypot(float x, float y) { return __builtin_hypotf(x, y); }
 inline constexpr float ldexp(float x, int exp) { return __builtin_ldexpf(x, exp); }
 inline constexpr float lgamma(float x) { return __builtin_lgammaf(x); }
 inline constexpr float lgamma_r(float x, int *signgamp) { return __builtin_lgammaf_r(x, signgamp); }
+inline constexpr float log(float x) { return __builtin_logf(x); }
 inline constexpr float log1p(float x) { return __builtin_log1pf(x); }
 inline constexpr float log10(float x) { return __builtin_log10f(x); }
-inline constexpr float log(float x) { return __builtin_logf(x); }
+inline constexpr float logb(float x) { return __builtin_logbf(x); }
 inline constexpr float modf(float x, float *iptr) { return __builtin_modff(x, iptr); }
 inline constexpr float nanf(const char *tagp) { return __builtin_nanf(tagp); }
 inline constexpr float nearbyint(float x) { return __builtin_nearbyintf(x); }