diff --git a/eigen/vacfun.f90 b/eigen/vacfun.f90
index caa5b2b9a7d27e1b53bc2c7c199f356b6f5b1763..e83399645f3506acc95f56cda9e1015f4c4bdcb9 100644
--- a/eigen/vacfun.f90
+++ b/eigen/vacfun.f90
@@ -53,7 +53,7 @@ CONTAINS
     REAL u(vacuum%nmzd,size(duz,1),input%jspins),ud(vacuum%nmzd,size(duz,1),input%jspins)
     REAL v(3),x(vacuum%nmzd), qssbti(2,2)
     !     ..
-    fac=MERGE(1.0,-1.0,jspin1>=jspin2)
+    fac=MERGE(1.0,-1.0,jspin1<=jspin2)
     ipot=MERGE(jspin1,3,jspin1==jspin2)
 
     tuuv=0.0;tudv=0.0;tddv=0.0;tduv=0.0