diff --git a/src/swiftest/swiftest_io.f90 b/src/swiftest/swiftest_io.f90
index 5d79f5969..657a80033 100644
--- a/src/swiftest/swiftest_io.f90
+++ b/src/swiftest/swiftest_io.f90
@@ -2116,7 +2116,7 @@ module subroutine swiftest_io_netcdf_write_frame_cb(self, nc, param)
 
             ! Populate coordinate values for l and m and export to hdf file
             allocate(lm_coords(l_dim_max))
-            do i = 0, l_dim_max
+            do i = 0, l_dim_max - 1
                lm_coords(i + 1) = i 
             end do