diff --git a/src/swiftest/swiftest_sph.f90 b/src/swiftest/swiftest_sph.f90
index aed6d4f0a..32187c62a 100644
--- a/src/swiftest/swiftest_sph.f90
+++ b/src/swiftest/swiftest_sph.f90
@@ -71,13 +71,13 @@ module subroutine swiftest_sph_g_acc_one(GMcb, r_0, phi, theta, rh, c_lm, g_sph,
                                                                 ! cssc * m = first derivative of ccss with respect to phi
 
                 ! m > 0
-                g_sph(1) = g_sph(1) + GMcb * r_0**l / r_mag**(l + 2) * (cssc * m * plm * sin(phi) / sin(theta) &
+                g_sph(1) = g_sph(1) - GMcb * r_0**l / r_mag**(l + 2) * (cssc * m * plm * sin(phi) / sin(theta) &
                                                                         + ccss * sin(theta) * cos(phi) &    
                                                                         * (dplm * cos(theta) + plm * (l + 1))) ! g_x
-                g_sph(2) = g_sph(2) + GMcb * r_0**l / r_mag**(l + 2) * (-1.0_DP * cssc * m * plm * cos(phi) / sin(theta) &
+                g_sph(2) = g_sph(2) - GMcb * r_0**l / r_mag**(l + 2) * (-1.0_DP * cssc * m * plm * cos(phi) / sin(theta) &
                                                                         + ccss * sin(theta) * sin(phi) &
                                                                         * (dplm * cos(theta) + plm * (l + 1))) ! g_y
-                g_sph(3) = g_sph(3) + GMcb * r_0**l / r_mag**(l + 2) * ccss * (-1.0_DP * dplm * sin(theta)**2  &
+                g_sph(3) = g_sph(3) - GMcb * r_0**l / r_mag**(l + 2) * ccss * (-1.0_DP * dplm * sin(theta)**2  &
                                                                         + plm * (l + 1) * cos(theta))          ! g_z
             end do
         end do