diff --git a/src/swiftest/swiftest_io.f90 b/src/swiftest/swiftest_io.f90
index 8209f2a34..4d1bcc185 100644
--- a/src/swiftest/swiftest_io.f90
+++ b/src/swiftest/swiftest_io.f90
@@ -1592,16 +1592,22 @@ module function swiftest_io_netcdf_read_frame_system(self, nc, param) result(ier
                                   "netcdf_io_read_frame_system nf90_inquire_dimension l_dimid"  )
             call netcdf_io_check( nf90_inquire_dimension(nc%id, nc%m_dimid, len = nc%m_dim_max), &
                                    "netcdf_io_read_frame_system nf90_inquire_dimension m_dimid")
-            
+           
+            if (nc%l_dim_max /= nc%m_dim_max) then
+               write(*,*) "Error reading in NetCDF file: c_lm requires l_dim_max = m_dim_max"
+               call base_util_exit(FAILURE,param%display_unit) 
+            end if
+
             if(.not. allocated(cb%c_lm)) allocate(cb%c_lm(nc%m_dim_max, nc%l_dim_max, 2)) 
             call netcdf_io_check( nf90_get_var(nc%id, nc%c_lm_varid, cb%c_lm, count = [nc%m_dim_max, nc%l_dim_max, 2]), &
                                   "netcdf_io_read_frame_system nf90_getvar c_lm_varid")
             
-            nc%lc_lm_exists = .true.
             if (abs(cb%j2rp2) > tiny(1.0_DP) .or. (abs(cb%j4rp4) > tiny(1.0_DP))) then
                write(*,*) "Error reading in NetCDF file: cannot use both c_lm and j2rp2/j4rp4"
                call base_util_exit(FAILURE,param%display_unit) 
             end if
+
+            nc%lc_lm_exists = .true.
          else
             if (allocated(cb%c_lm)) deallocate(cb%c_lm)
             nc%lc_lm_exists = .false.