diff --git a/tests/test-up.cxx b/tests/test-up.cxx
index 362384784..d5ae7c1b1 100644
--- a/tests/test-up.cxx
+++ b/tests/test-up.cxx
@@ -28,18 +28,25 @@ int main() {
 	Point3D pc = sgGeodToCart( pgd );
 	cout << "  cartesian = " << pc << endl;
 
-	sgMat4 UP;
+	sgMat4 GEOD_UP;
 	sgVec3 geod_up;
-	sgMakeRotMat4( UP, lon, 0.0, -lat );
-	sgSetVec3( geod_up, UP[0][0], UP[0][1], UP[0][2] );
+	sgMakeRotMat4( GEOD_UP, lon, 0.0, -lat );
+	sgSetVec3( geod_up, GEOD_UP[0][0], GEOD_UP[0][1], GEOD_UP[0][2] );
 	cout << "  geod up = " << geod_up[0] << ", " << geod_up[1] << ", "
 	     << geod_up[2] << endl;
 
+	sgMat4 GEOC_UP;
+	sgVec3 geoc_up;
+	sgMakeRotMat4( GEOC_UP, lon, 0.0, -lat_geoc * RAD_TO_DEG );
+	sgSetVec3( geoc_up, GEOC_UP[0][0], GEOC_UP[0][1], GEOC_UP[0][2] );
+	cout << "  geoc up = " << geoc_up[0] << ", " << geoc_up[1] << ", "
+	     << geoc_up[2] << endl;
+
 	double slope = geod_up[2] / geod_up[0];
 	double intercept = pc.z() - slope * pc.x();
 	cout << "  Z intercept (based on geodetic up) = " << intercept << endl;
 
-	slope = pc.z() / pc.x();
+	slope = geoc_up[2] / geoc_up[0];
 	intercept = pc.z() - slope * pc.x();
 	cout << "  Z intercept (based on geocentric up) = " << intercept << endl;