diff --git a/src/swiftest/swiftest_sph.f90 b/src/swiftest/swiftest_sph.f90
index 4b5d8b19f..484ac8dae 100644
--- a/src/swiftest/swiftest_sph.f90
+++ b/src/swiftest/swiftest_sph.f90
@@ -85,7 +85,7 @@ module subroutine swiftest_sph_g_acc_one(GMcb, r_0, phi_cb, rh, c_lm, g_sph, GMp
                 if ((m+1) <= l) then
                     lmindex = PlmIndex(l, m+1) 
                     plm1 = p(lmindex) 
-                    if(m ==. 0) then
+                    if(m == 0) then
                         plm1 = plm1 * sqrt(((l + m + 1) * (l - m)) / 2.0) ! renormalize plm1 to the norm of plm
                     else 
                         plm1 = plm1 * sqrt((l + m + 1) * (l - m) * 1.0)       ! renormalize plm1 to the norm of plm