diff --git a/src/mpblock.c b/src/mpblock.c
index 610594c..37c0175 100644
--- a/src/mpblock.c
+++ b/src/mpblock.c
@@ -44,12 +44,11 @@ long double meridian_arc(long double lat0, long double lat1)
 		c += sqr(double_fac(2 * j - 3) / double_fac(2 * j) * powl(FLAT_3, j));
 	m = c * (lat1 - lat0);
 
-	for (k = 1; k < 6; k++) {
+	for (k = 1; k < 11; k++) {
 		c = 0;
 		for (j = 0; j < 11; j++)
 			c += double_fac(2 * j - 3) / double_fac(2 * j) * double_fac(2 * j + 2 * k - 3) / double_fac(2 * j + 2 * k) * powl(FLAT_3, k + 2 * j);
-		c /= k;
-		c *= powl(-1.0l, k) * (1 - sqr(2 * k));
+		c *= powl(-1.0l, k) * (1 - sqr(2 * k)) / k;
 		m += c * (sin(2.0l * k * lat1) - sin(2.0l * k * lat0));
 	}
 
diff --git a/src/vincenty.c b/src/vincenty.c
index 984c31a..99d0926 100644
--- a/src/vincenty.c
+++ b/src/vincenty.c
@@ -62,7 +62,7 @@ long double helmertA(long double calp)
 	usq = calp * ECC2;
 	k1 = sqrtl(1.0l + usq);
 	k1 = (k1 - 1.0l) / (k1 + 1.0l);
-	for (k = 0; k < 11; k++)
+	for (k = 0; k < 8; k++)
 		A += sqr(double_fac(2 * k - 3) / double_fac(2 * k) * powl(k1, k));
 	A /= (1 - k1);
 	return A;