diff --git a/src/swiftest/swiftest_module.f90 b/src/swiftest/swiftest_module.f90
index 103af911e..dab54a4ea 100644
--- a/src/swiftest/swiftest_module.f90
+++ b/src/swiftest/swiftest_module.f90
@@ -1866,7 +1866,7 @@ module subroutine swiftest_sph_g_acc_one(GMcb, r_0, phi, theta, rh, c_lm, g_sph,
          real(DP), intent(in), dimension(:)          :: rh          !! distance vector of body
          real(DP), intent(in), dimension(:, :, :)    :: c_lm        !! Spherical Harmonic coefficients
          real(DP), intent(out), dimension(:)         :: g_sph       !! acceleration vector
-         real(DP), dimension(:),   intent(in),  optional :: GMpl    !! Masses of input bodies if they are not test particles
+         real(DP), intent(in),  optional :: GMpl                    !! Mass of input body if it is not a test particle
          real(DP), dimension(:),   intent(inout), optional :: aoblcb  !! Barycentric acceleration of central body (only for massive input bodies)
       end subroutine swiftest_sph_g_acc_one
 
diff --git a/src/swiftest/swiftest_sph.f90 b/src/swiftest/swiftest_sph.f90
index 3a561e89a..1c0f5962d 100644
--- a/src/swiftest/swiftest_sph.f90
+++ b/src/swiftest/swiftest_sph.f90
@@ -31,7 +31,7 @@ module subroutine swiftest_sph_g_acc_one(GMcb, r_0, phi, theta, rh, c_lm, g_sph,
         real(DP), intent(in), dimension(:)          :: rh          !! distance vector of body
         real(DP), intent(in), dimension(:, :, :)    :: c_lm        !! Spherical Harmonic coefficients
         real(DP), intent(out), dimension(:)         :: g_sph       !! acceleration vector
-        real(DP), dimension(:),   intent(in),  optional :: GMpl    !! Masses of input bodies if they are not test particles
+        real(DP), intent(in),  optional :: GMpl                    !! Mass of input body if it is not a test particle
         real(DP), dimension(:),   intent(inout), optional :: aoblcb  !! Barycentric acceleration of central body (only for massive input bodies)
      
         ! Internals