diff --git a/Sources/General/residue.f90 b/Sources/General/residue.f90
index aefba0f..f947227 100755
--- a/Sources/General/residue.f90
+++ b/Sources/General/residue.f90
@@ -9,6 +9,7 @@ SUBROUTINE residue_par (gcr, gcz, gcl)
       USE parallel_vmec_module, ONLY: tlglob_arr, trglob_arr,                  &
                                       lactive, SAXLASTNTYPE
       USE blocktridiagonalsolver, ONLY: L_COLSCALE
+      USE dbgout
 
       IMPLICIT NONE
 !-----------------------------------------------