diff --git a/src/msspec/spec/fortran/eig/common/plotfd.f b/src/msspec/spec/fortran/eig/common/plotfd.f
index 65fd858..b877230 100644
--- a/src/msspec/spec/fortran/eig/common/plotfd.f
+++ b/src/msspec/spec/fortran/eig/common/plotfd.f
@@ -8,6 +8,7 @@ C
 C      INCLUDE 'spec.inc'
 C
 C
+      USE DIM_MOD
       USE APPROX_MOD
       USE FDIF_MOD
       USE INIT_L_MOD, L => LI, I2 => INITL, I3 => NNL, I4 => LF1, I5 =>