diff --git a/include/QF/mathlib.h b/include/QF/mathlib.h
index 96e78e9b0..d34c86f1d 100644
--- a/include/QF/mathlib.h
+++ b/include/QF/mathlib.h
@@ -413,6 +413,7 @@ void RotatePointAroundVector (vec3_t dst, const vec3_t axis,
 							  const vec3_t point, float degrees);
 
 void QuatMult (const quat_t q1, const quat_t q2, quat_t out);
+void QuatMultVec (const quat_t q, const vec3_t v, vec3_t out);
 void QuatInverse (const quat_t in, quat_t out);
 void QuatExp (const quat_t a, quat_t b);
 void QuatToMatrix (const quat_t q, vec_t *m, int homogenous, int vertical);
diff --git a/libs/util/mathlib.c b/libs/util/mathlib.c
index f33ecf82e..1bdc804ac 100644
--- a/libs/util/mathlib.c
+++ b/libs/util/mathlib.c
@@ -181,6 +181,20 @@ QuatMult (const quat_t q1, const quat_t q2, quat_t out)
 	out[0] = s;
 }
 
+VISIBLE void
+QuatMultVec (const quat_t q, const vec3_t v, vec3_t out)
+{
+	vec_t      s;
+	vec3_t     tv;
+
+	s = -DotProduct (q + 1, v);
+	CrossProduct (q + 1, v, tv);
+	VectorMultAdd (tv, q[0], v, tv);
+	CrossProduct (q + 1, tv, out);
+	VectorMultSub (out, s, q + 1, out);
+	VectorMultAdd (out, q[0], tv, out);
+}
+
 VISIBLE void
 QuatInverse (const quat_t in, quat_t out)
 {
diff --git a/libs/util/test/test-quat.c b/libs/util/test/test-quat.c
index 0b2defb13..63f06671d 100644
--- a/libs/util/test/test-quat.c
+++ b/libs/util/test/test-quat.c
@@ -82,6 +82,52 @@ fail:
 	return 0;
 }
 
+static int
+test_rotation2 (const vec3_t angles)
+{
+	int         i;
+	vec3_t      forward, right, up;
+
+	quat_t      quat;
+	vec3_t      f, r, u;
+	vec3_t      vf = {1,  0, 0};
+	vec3_t      vr = {0, -1, 0};
+	vec3_t      vu = {0,  0, 1};
+
+	AngleVectors (angles, forward, right, up);
+
+	AngleQuat (angles, quat);
+	// rotate forward vector
+	QuatMultVec (quat, vf, f);
+	// rotate right vector
+	QuatMultVec (quat, vr, r);
+	// rotate up vector
+	QuatMultVec (quat, vu, u);
+
+	for (i = 0; i < 3; i++)
+		if (!compare (forward[i], f[i]))
+			goto fail;
+
+	for (i = 0; i < 3; i++)
+		if (!compare (right[i], r[i]))
+			goto fail;
+
+	for (i = 0; i < 3; i++)
+		if (!compare (up[i], u[i]))
+			goto fail;
+	return 1;
+fail:
+	printf ("\n\n%g %g %g\n\n", angles[0], angles[1], angles[2]);
+	printf ("%g %g %g\n", forward[0], forward[1], forward[2]);
+	printf ("%g %g %g\n", right[0], right[1], right[2]);
+	printf ("%g %g %g\n\n", up[0], up[1], up[2]);
+
+	printf ("%g %g %g\n", f[0], f[1], f[2]);
+	printf ("%g %g %g\n", r[0], r[1], r[2]);
+	printf ("%g %g %g\n", u[0], u[1], u[2]);
+	return 0;
+}
+
 int
 main (int argc, const char **argv)
 {
@@ -92,5 +138,10 @@ main (int argc, const char **argv)
 		if (!test_rotation (test_angles[i]))
 			res = 1;
 	}
+
+	for (i = 0; i < num_angle_tests; i ++) {
+		if (!test_rotation2 (test_angles[i]))
+			res = 1;
+	}
 	return res;
 }